When arguing why it’s better than alternatives, the talking point is that “it’s open-source!” But when it’s (rightfully) pointed out that this doesn’t leave much of a defensive moat, the open-source philosophy gets thrown under the bus.

Yes, yes...it’s “open core”. That just means that it’s 10% more difficult to clone and replicate the business. Mark my words: someday, Gitlab will do something to piss off the “community”, and this will quickly happen.