As a developer I don't like it, but reality doesn't have to appease me.
In my view and experience, Zulip is a collaboration platform for groups who want to get shit done. I wouldn't recommend it for a "place to hang out".
People who are serious about achieving something will use a laptop. Similarly, in a cousin comment - they will watch a short onboarding video.
No platform is "intuitive" for everyone. WhatsApp and Signal are "basically just SMS" so they can lean on the knowledge phone users built in the 00s and 10s. Anything else is a new mental model and takes some adjustment.
EDIT: also if you are an open source community, or a company, and you choose Discord for your support/project collab community... do better. (Looking at you CloudFlare)