My guess is that this actually regarded as a feature in the wider #fediverse. At least in the Mastodon community it is. Toots not being searchable/indexed and you discover topics and people to follow by looking for hashtags and organically setup and control your own home feed. This, leading to much frustration for many who've moved over from Twitter.
Reasons being that it should not be easy for big tech (and others) to just slurp up and make peoples data open publicly for a wider audience through public search engines. A level of privacy and owning ones own data has been a priority over the inconvenience of not being as discoverable.
Of course the same thinking does not apply or map equally well to the #threadiverse as it does to Mastodon. I'm sure there are workarounds and a way to make this more seamless for users, but this is just getting started. It was never an issue when everything was on a small number of instances which everyone knew about.