I think you're right, other solutions require dev work, but centralization caused by default instances is usually irreversible, they tend to grow bigger over time (and more generally in federations, big instances are getting bigger - email, matrix and mastodon are good examples)
An ideal protocol should work like RSS. There, the cost of participation for content consumers is almost zero. One just needs a client. The cost of participation for content producers is low (one can use any static site generator), and they enjoy all the benefits of decentralized infrastructure.
How we can get to that point with ActivityPub? Some ideas:
- More efficient servers. Instance setup should be as simple as creating a static website with an RSS feed
- Read-only accounts. These users can participate as content consumers, but the cost for instance operators is much lower because they don't require moderation.
- Universal UIs. People shouldn't be forced to create accounts on different federated services.
- Pulling from outbox. Instance blocks punish content consumers for no reason, and this can be fixed by switching to pull model in some situations.