Hi, thanks for taking your time to respond to people on Twitter!
Please note that I’m neither a Mozilla employee nor was I involved in that discussion.
I’d suggest to read 1477667 - [meta] Remove feed reader and live bookmarks support from Firefox, most notably comment 3, which answers one of your statements:
[…] this code is old and bogus, it has quite a few security problems, and prevents a bunch of optimizations from happening. It’s not sustainable and nobody wants to maintain it in current shape, nor we have the resources to write it from scratch (and maintain it then).
Keeping features around because “it works” can lead to several crucial problems. Maintainability of software is important and nobody wants an insecure, bloated browser, right?
IMHO the best way forward in terms of support is to recommend add-ons which can do this:
And here’s a curated list of helpful add-ons: