you can do a puppet bridge for your discord account so it bridges all the guilds your in to matrix without needing discord guild admins to add the bridge to it
did you host your own matrix homeserver or use matrix.org? that can change how fast it feels massively and yeah built in moderation tools are pretty much nonexistant github.com/the-draupnir-project/Draupnir is the only moderation bot that you can run to ban users from all rooms at once if they break your rules and lets you subscribe to banlists so if a user spams in other rooms that have write access and gets added they’ll be banned from your rooms as well