[lolinder]

The key difference between SMTP and ActivityPub is that SMTP arrived on the scene in an era when getting started on the internet (sorry, ARPANET) at all was a major technical feat. The median internet user in the two decades following the introduction of SMTP was plenty competent enough to handle the complexities of email, and once email became the standard way to communicate everyone had to figure it out. At first it was all that we had, and by the time centralized platforms started making things easier the network effects were so strong that they had to support SMTP.

Some people are putting Mastodon forward as a replacement for a centralized platform, but now the network effects are working in the same direction as the complexity friction—both are pushing you towards centralized platforms and away from Mastodon and company. For most people there's no incentive to overcome the barriers because they would be the first in their social circles to attempt it, and the centralized platforms so far have had little motivation to support ActivityPub because their users don't expect to interact with that ecosystem. If Threads really does implement ActivityPub I could see that changing, but that remains to be seen.

This doesn't mean that Mastodon doesn't have a place right now—if you're looking for a community that is specifically filtered to exclude those who aren't above average in technical competency, it'll do nicely. But it cannot serve the median internet user today.