Earlier quoted context omitted.
One of the ways instance blocks are used, in practice, is to discourage other instances from enforcing boundaries. For example, one of the biggest and oldest Mastodon instances recently blocked an entire up-and-coming instance because they banned one person who has a trail of allegations that they solicited underage kids for sex. A number of other, smaller instances also block instances that ban another alleged seria…
Does the functionality of blocking just a single user from an instance not exist with Mastodon? This does bring up an important point however, in that the largest instances that will exist may not be the one that curates and manages the instance/ecosystem/users on the ecosystem as well or as reasonably, however creates a space (or bubble) of popular reaction - say being only "80%" compassionate vs. fully understandin…
If you're building a purely general purpose instance or a free speech themed one it's fine to not block this sort of instance.
It's okay to have this "net split". It's a system of curation. It encourages smaller instances.
Mastodon is also heavily used by minority / LGBT communities that deal with abuse and harassment a lot, often for merely existing. And often a "free speech" instance or worse a "no moderation" instance will attract that sort of person.