I don't think that's a sound assumption. Big companies often outpace their contract pipeline. Some so it by design. Having staff "on the bench" is anticipation of work to come.
Atlassian derives the bulk of their income through subscriptions, not contracted projects. That's my assumption, but I think it's defensible.
I think if your point were true for them they would, as you suggest, keep consuming that project queue. Nobody company doesn't want revenue. But since they're looking at the other side of the ledger, I suspect they're not oversubscribed.
Of course if somebody wants to chime in and say "I tried to give atlassian money to get work done quickly and they weren't interested" I'm open to being proven wrong. :)