@mttaggart Yes, you need some easy migration for the not so technically inclined. Because those are the ones that would use those services.
And you‘d need to standardize on absent of services to make migration viable. And of course you have to be at least as good as the „free“ services, so that a large number of people would use those services.
I‘m all for self-hosting but not everyone has the time or ability to run their own services. Just running your own mail service is complex enough.