However I'm constantly adding new roles which are really just groups of users. I would say 90% of all the Discord roles I've ever created have no permissions associated with them at all and just exist to ping a group of users (or act as a tag for bots).
Maybe that's served by a different feature in Matrix for user groups. If so, that's still not quite as useful, because sometimes later on you decide the group needs a permission (e.g. a casual gaming group has grown enough to justify having it's own channel).