This has been brought up on HN before, and people smarter than me identified that this view is about 10 years out of date. Yes it's a bunch of XEPs, but there are standardized "sets" apparently that include all of the things any other similar tools do. It sounds like only very niche old/minimal XMPP clients don't support encryption by default for example, and virtually all servers have supported it for many years.
> Yes it's a bunch of XEPs, but there are standardized "sets" apparently
If the answer to "it's confusing" is "there are apparently standardised sets", it sounds like it is, indeed, confusing :-).
And unlike Matrix(/Element), it works most of the time.
Is there a recommended or "blessed" server and client combo for someone who just wants to migrate their friends off discord?
The main site https://xmpp.org/software/ lists lots of different options but I have no idea what core/advanced means and comparing all of these would take ages.