> shifting focus towards requiring WebComponents (...)
I can't help but read this as "Palemoon is stuck in the past wrt standards", which is a self-inflicted problem from what Palemoon is (a fork of an old version of Firefox), and the resources they have to maintain it (only one person, IIRC). For the same reason that building a new browser engine is a ton of work, maintaining a fork of an old engine is a ton of work. Take that from someone who has spent a lot of time backporting security fixes for old versions of Firefox in Debian stable back when Debian was not updating to new major versions of Firefox ESR (back when Debian was still calling it Iceweasel).
It is not the past. There are two mutually exclusive views of the web. As a set of protocols set to allow individual humans to share information about things they love and the web as a set of protocols to make a living.
Profit motivated web presences want views, they want attention, they need nine 9s uptime, need to be able to do monetary transactions absolutely securely, and they want to be an application not a document. They live and die on the eternal wave of walled garden's recommendation engines because that's the network effect and that's where money flows. It doesn't matter if this means extremely high barriers to entry because money solves everything. It means JS VM applications and constant churn in standards. Web components, HTML without HTML, is one aspect of this.
Individuals' websites are freeform presentations about the things that person is interested in. They are the backyard gardens of the mind and the most important thing is lowering the friction from thought to posting. There's no need to get tons of traffic instantly (or ever), they're mostly time insensitive. They're documents. They're stable. They're actually HTML.
The big corporate browsers, Chrome, Firefox, and Safari are browsers designed for the corporate money web and they are becoming absolutely useless for actual web surfing. Pale Moon, and other browsers, are still focused on being browers. This isn't the past, it's the point.
People who have an older computer and want to access newer systems. I helped someone who had an older Mac and wanted to access a university system (Canvas LMS) that required modern technologies. Nothing but Pale Moon worked; the alternative was to ditch the computer, but it was pristine.
I was going to see if perhaps the abuse of Issues was what annoyed the maintainer more than the primary reason).
That's one of big downsides of a world where 99.99% of people create nothing (in terms of code or docs): when Github wasn't as popular many "consumers" didn't have accounts.
Now they do, and often tend to turn Issues into a discussion forum (which, contrary to Tobin's assessment, is a testament to the success of Github's UX, but not of the kind devs and power users want). The easiest way to deal with that is what Tobin did. Mirror the source to Github and lock (or ignore) GH issues.
I can't help but read this as "Palemoon is stuck in the past wrt standards", which is a self-inflicted problem from what Palemoon is (a fork of an old version of Firefox), and the resources they have to maintain it (only one person, IIRC). For the same reason that building a new browser engine is a ton of work, maintaining a fork of an old engine is a ton of work. Take that from someone who has spent a lot of time backporting security fixes for old versions of Firefox in Debian stable back when Debian was not updating to new major versions of Firefox ESR (back when Debian was still calling it Iceweasel).