These frustrations are understandable. On the whole one could say that saying "Implement #ActivityPub and federate" raises wrong expectations.
And that it is more accurate to say that AS/AP et al gives you foundation stones and building blocks that constitute a framework for federated app development. Unfortunately there's been a lot of ad-hoc interoperability and protocol decay. The trend is not to maturity but chaos.
I took notes on major challenges: https://discuss.coding.social/t/major-challenges-for-the-fediverse/67