Ah, the joys of open source: where "nobody has implemented 'mark all as read' on a space yet" is extrapolated to "half-baked and just a bunch of hacks".

Custom emojis & sticker packs exist as per MSC1951 (thanks for linking it), and implemented in various clients. The fact the data is stored in a room shouldn't exactly be a surprise, given 'rooms' (i.e. persistent decentralised pubsub topics) are the main primitive for storing data in Matrix, much as everything is a file in unix.

Sorry you feel Matrix feels half-baked; meanwhile we're busy doing a major iteration as per https://fosdem.org/2023/schedule/event/matrix20 and https://element.io/blog/element-x-experience-the-future-of-e.... Right now the target is more WhatsApp/Signal/iMessage style messaging than Discord/Slack/Teams, but we'll (re)address the latter eventually.