Earlier quoted context omitted.
Those are all issues as well, but brigading is absolutely a thing.
Blocking doesn't really fix the brigading problem, regardless of whether people need to log out or not. Most X users will just post a screenshot of the tweet, breaking accessibility in the process and disassociating the original author from the thread against their will. This isn't always a good thing, as it leads to people being surprised by crowds of strangers suddenly screaming at them and not being able to see th…
But that means the blocking worked. Another person will now have to go to the extra effort of either finding that tweet or going directly to the profile to interact with them. And those extra steps were exactly the feature the blocking provided. It changes "click reply, type 'kill yourself you '" into "login into non-blocked account, retype part of the text from the screenshot, search, find the matching tweet, reply, type". And that's a lot of work for a quick response.
Sure, it won't stop everyone. It reduces the effects though.