We looked at it briefly, but the number of components make it look more of a tech demo than a product meant to be installed on-prem. Redis, Postgres, Rabbitmq and Memcached just to run a chat?
It is neither a tech demo nor a product, it is a mature open source project.
In fact, in my mind tech demos tend towards having fewer mature components.
> Redis, Postgres, Rabbitmq and Memcached just to run a chat
That set of dependencies seems quite normal to me for a mature project. Mastodon (the most popular open-source-twitterish-thing) has a similar set of dependencies, and is also effectively just chat as you say.
Discourse, a popular open source forum, is also basically just chat, and has a similar set of dependencies.
In the case of zulip, you can even use a hosted version and avoid running anything yourself.
I don't understand why its totally normal set of dependencies turns you off so harshly. I'll happily take a project using redis/postgresql/etc instead of trying to build its own versions of those baked into the binary because components like postgres/redis/etc have great documentation, tooling for metrics and monitoring, etc... If the project bakes its own stuff in itself to avoid taking on dependencies, I doubt it will either be as good or as easy to manage.