docs(intro): Update and clarify goals/motivation

To help calibrate our collaboration, I went uninhibited with these changes including:

- assumptions about history I don't actually know:
  "this project was one of the early entrants"
- description of the yt-dlp/ytdl-sub division of labor I'm not actually certain about
- max opinion, both about this project and the domain in general
- max cheeky/fun writing tone, with the intention of being personable
- max editor's red pen, cut mercilessly

IOW, review carefully and reject early and often to help me submit future changes that
require less review and revision. To that end, give me more rather than less feedback on
this change in particular.

I include an endorsement of Pinchflat because [they do the same for
ytdl-sub](https://github.com/kieraneglin/pinchflat?tab=readme-ov-file#what-it-does). It
would be my next choice if ytdl-sub couldn't meet my needs or vanquished me.  More
than that link, in other Reddit comments and the like, the Pinchflat author clearly
expresses preference for ytdl-sub as their own "next option".

Author: rpatterson

docs/source/index.rst

@@ -12,5 +12,3 @@ ytdl-sub User Guide
   config_reference/index
   faq/index
   deprecation_notices
-
-.. note:: The docs are heavily work-in-progress. Please bear with us while we're under construction!

docs/source/introduction.rst

@@ -8,10 +8,19 @@ What is ytdl-sub?
 .. _plex: https://github.com/plexinc/pms-docker
 .. _emby: https://github.com/plexinc/pms-docker
 
-``ytdl-sub`` is a command-line tool that downloads media via `yt-dlp`_ and prepares it for your favorite media player (`Kodi`_, `Jellyfin`_, `Plex`_, `Emby`_, modern music players).
+``ytdl-sub`` is a command-line tool that builds on and orchestrates `yt-dlp`_ to
+download media from YouTube and/or other online services. It provides a declarative,
+expressive YAML configuration system that allows you to describe which media to download
+and how it should appear in your media library servers and applications such as
+`Jellyfin`_, `Plex`_, `Emby`_, `Kodi`_, modern music players, etc..
 
-Visual examples
-===============
+To these ends, ``ytdl-sub``:
+
+- wraps and runs `yt-dlp`_, per your configuration to:
+  - download the media, remux and/or optionally transcode it
+- prepares additional metadata both embedded and in external files
+- renames the resulting files
+- places them in your library
 
 .. figure:: https://user-images.githubusercontent.com/10107080/182677243-b4184e51-9780-4094-bd40-ea4ff58555d0.PNG
   :alt: The Jellyfin web interface, showing the thumbnails of various YouTube shows.
@@ -34,10 +43,52 @@ Visual examples
   SoundCloud albums and singles in MusicBee
 
 
-Why ytdl-sub?
--------------
-There is a lack of open-source tools to download media and generate metadata to play it in these players. Most solutions involve using multiple tools or bash scripts to achieve this. ``ytdl-sub`` aims to consolidate all of this logic into a single easy-to-use application that can run automatically once configured.
+Motivation
+----------
+
+`yt-dlp`_ has grown into a well maintained, central repository of the intricate,
+inscrutable, and extensive technical knowledge required to automate downloading media
+from online services. When those services change their APIs or otherwise change
+behavior, `yt-dlp`_ is the central, low-level tool to update. It does a best-in-class
+job at that task, and it does that job more effectively by narrowing focus to just that.
+As much knowledge as it encapsulates and as well as it does that, it still requires a
+great deal of additional knowledge to make its output accessible to end-users. Mostly
+this gap is about extracting and formatting metadata and correctly placing the resulting
+output files in a media library.
+
+A number of tools, applications, and other projects have grown up around that central
+`yt-dlp`_ pillar to fill in those gaps, and this project was one of the early
+entrants. Many are `full-featured services that provide web UIs`_ including some that
+`provide media player web UIs`_. Most of those other projects necessarily narrow their
+scope to provide a more polished and integrated user experience.
+
+Similarly, ``ytdl-sub`` can run automatically to accomplish the same goals, but aims to
+serve users that need lower-level control and/or have use cases not covered by the more
+narrow scope of those other projects. To some degree, this makes this project
+intrinsically less user friendly and requires more technical experience or learning.
+
+Want something that "Just Works", try one of the other projects; we recommend
+`Pinchflat`_ as the next step towards that end. Want to download from more than just
+YouTube? Don't like the other restrictions inherent in the goals of those other
+projects? Have unique use cases? Then dig in, learn, and we hope ``ytdl-sub`` gives you
+enough rope and `a foot-gun`_ to get you there.
+
+.. _`full-featured services that provide web UIs`:
+   https://github.com/kieraneglin/pinchflat
+.. _`provide media player web UIs`:
+   https://www.tubearchivist.com/
+.. _`Pinchflat`: `full-featured services that provide web UIs`_
+.. _`a foot-gun`: https://en.wiktionary.org/wiki/footgun
+
 
 Why download instead of stream?
 -------------------------------
-We believe it is important to download what you like because there is no guarantee it will stay online forever. We also believe it is important to download it in such a way that it is easy to consume. Most solutions today force you to watch/listen to your downloaded content via file system or web browser. ``ytdl-sub`` aims to format downloaded content for any media player.
+
+Most of the tools in this `yt-dlp`_ ecosystem serve a similar set of larger, more
+general use cases, and so does ``ytdl-sub``:
+
+- Don't rely on profit-driven corporate persons to keep more obscure content available.
+- Even if they do, don't depend on them to make it possible to use it in different ways.
+- Even when you pay, don't count on them not inserting ads later.
+- Regardless, don't depend on them to curate content for yourself and/or your family.
+- Free yourself and/or your family from what the algorithm would feed them next.