Slack's advertisement for unlimited users was based on their product's design.Their hard limit is perfectly reasonable because the interface wasn't really designed to handle 10k users in the first place.I want to point out that communities are increasingly using Slack, and many of them are also in the thousands of users.Slack does nothing to discourage this, aside from posting warnings about archiving messages.You can always Email people with something to the effect of, "Hey!We've turned off your account, if you visit the site again, we'll turn it back on, no big deal"well said!It's pretty clear that Slack is not, and never will be, built for this use-case.
You've made your problems the engineering problems of another team, except in the other team's case, they're accountable to investors and a bottom line.
Using a BIGINT for your primary key will get you a max of 18446744073709551615.
Should we complain that we can't go higher in any application that uses one of these?
The real problem is that they have an undocumented user limit. But that does not mean Slack is under any obligation to support your use case, especially when they are pretty clear about what Slack is for.
Like I said, I'm pretty sure we're the first community to hit this limit. It's right there on the homepage: "Slack is a platform for team communication."A course with hundreds of thousands of students is in no way a "team."I might be misreading the post, but my interpretation was that the audience is other large communities, MOOCs, and other loosely affiliated organizations that may want to try Slack, not the Slack team itself.