1. Mattermost's "Rug Pull" and Licensing Restrictions
Users decry the unannounced addition of message history limits (e.g., 10k posts) to self-hosted free editions as a bait-and-switch from open source to open core.
"Mattermost only got where it is today because of the open-source community... [now] enforce a ridiculously small message limit... without announcing it" - Zephilinox.
"Classic rug pull though" - AmazingTurtle.
"Open Source is dying... supply-chain control is profitable" - csomar.
2. Impracticality of Forking
Forking is dismissed as burdensome due to rebasing, security patches, and maintenance.
"Maintaining your own fork is a ton of work... The open source community really needs to stop with the 'just fork it' mindset" - mort96.
"Forking it would be a major undertaking as the number of vulnerabilities... is quite high like 5 a month" - yread.
3. Alternatives to Mattermost
Frequent recommendations for Zulip, Matrix, XMPP, IRC, or forks like MostlyMatter.
"Highly recommend looking at Zulip as an alternative... even better than Slack" - carolosf.
"Use matrix instead. Or zulip. Or xmpp. Or IRC" - ptman.