Isn’t the “solution” for Sentry that deploying it is such a pain in the ass that no one bothers to really do this? I haven’t checked in years but that always seemed like the real competitive blocker?
But then again I think this only prevents small players from "competing" by self-hosting, so the revenue loss there would be minimal either way. Large enterprises are too incompetent to even self-host a single self-contained binary, so for those the availability of source code and ease of hosting would make no difference, they would still use the SaaS.
That Sentry is a pain to deploy is not really intentional, it just happened over the years. However because it's a pain to deploy it also opens up a market for people that create managed deployments so I would say, that if anything, it made it worse. For self deployed Sentry you do not need to pay cent, the license explicitly allows it.
I'm personally on the fence how much of it is intentional... from the_mitsuhiko's side it probably isn't, but "the purpose of a system is what it does" and all.