Often we see people asking questions or advice, and it happens that after the question has been answered or the advice has been accepted, people keep boosting the post - often without even reading the thread. This only generates noise and wastes bandwidth.
Proposed solution:
Add a flag to the post indicating it has been answered. Optionally, be able to lock the conversation (not merely mute it) to prevent further replies and/or boosts.
Addendum: Users MUST be allowed to filter topics by their following list!
This will prevent noise and spam from seeping in.
Also, categories / topics aren't necessarily hard; they can operate like circles (I've posted on how to implement circles before), with a difference: topics don't PM the messages to their subscribers, they merely post and their followers subscribe to them. You can freely find a topic, but should be able to (optionally) control who's approved to submit or reply.
So here's the interesting idea: categories / topics should be globally accessible, but have moderators PER INSTANCE. This means that a topic in a server can have its own reply-to controls. Followers of the global topic should be able to read topics on their federated (global) timelines, but they can't reply if a remote topic does not allow them to.
Global Topic { instance 1 topic, instance 2 topic, ... instance N topic }
This results in the following requirements:
1) Topics should act like normal accounts; to post to a topic, you PM to it and the topic will relay.
2) Topics should be able to be local only and NOT to federate - this means blocking the same topic from the federated timelines.
3) Topics MUST require approval by server admins
4) Topics MUST require local, per-instance moderators who need full control over them.
5) Topics MUST be subject to an instance's federation rules.
While exercising my self-control not to be a reply-guy, I realized something:
Not all boosts are equal. A rough categorization of boosts yiels the following:
* Money emergencies
* Political action
* Denouncing police crimes 
* Jokes and memes
* Jokes and memes about gender stuff
* Jokes and memes on more personal stuff (aimed at a limited audience, but for which replies can't be disabled because Mastodon can't do that)
* Takes worth discussing
* Personal discussions whose boosts were asked at a specific audience but then an asshole comes in and starts replying
If I turn off boosts because I can't help being the asshole, I'm also turning off boosts belonging to the other categories.
(And a remark: if a system has to depend on the good will / self control of the majority of users to work well, IT SUCKS.)
How to avoid this: We need a way to categorize and filter boosts by topic. hashtags don't cut it because hashtags require public posting, and that renders them useless.
Conclusions:
1) We need the capacity to search our followed posts by tag, even if they're followers only. Boosts must STILL be except from searching if we don't follow the posters.
2) We still need a way to disable replies beforehand. (aka enforcing "don't @ me")
3) We need moderated categories, aka subreddits. Surprise, surprise.
Cyber Yuki 
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