Consider linear power levels instead of the current system

[Biep]

Is your suggestion related to a problem? Please describe.
It is difficult to remove default rights if one cannot demote users.
Also, power levels, the public/private states of rooms, and invitations, kicks, and bans currently seem separate things, which they don't need to be.

Describe the solution you'd like
I'd like the default level of users for any room to be some fixed number > 0, and make those levels persistent when leaving/re-entering.
Let's suppose the top admin level is set to 1000 (instead of the current 100) for ease of talking, and the default user level is set to 100.
That way, setting the threshold for entering below 100 would create a public room, and setting it above 100 would create a private room. Invitations would just reduce to changes of power level + a message with a link to the room.
If guests had a default level of, say, 50, one could open the room for users, whereas guests would still need an invitation.
If the threshold for being in a room were 5, kicking would reduce to setting the level temporarily below 5, and banning to setting it permanently below 5.
If the level for reading messages were 10, reading reactions were 15, writing reactions were 20, and writing messages were 25, one could easily demote users without kicking or banning them - still giving new entrants full interaction rights, but being able to silence abusers while still allowing them to read what the "good citizens" write. There could be power thresholds for having their old messages visible (so that, say, only moderators and higher can read the stuff that got them demoted).
In other contexts, the reaction threshold might be higher than the writing threshold, and the reacting-to-one's-own messages threshold between those two. (That is one reason why I like a 1000-step threshold by the way: one can move thresholds around quite a bit without having to renumber everything to make space. But obviously this proposal does not depend on that in any way.)

[Biep]

Setting the read level for certain messages higher would make them visible for users with higher power levels only. This is useful e.g. for sending a message to the admins, or for making an offending message invisible without removing the audit trail.

[TR-SLimey]

Better yet, make the max power level 10,000 so admins can be

@ara4n ;)

[t3chguy]

The default limit is imposed by Synapse