Alternative take: I can't speak for BitBucket because I've never used it, but I've had enough time with JIRA and Confluence to last a lifetime, and these products are so bad - so clunky, so slow, so much friction in the UI - that I can't really see what useful value adding work Atlassian's 16,000 employees have actually been delivering. From that perspective losing 1600 of them seems like it's not likely to make much difference since, from my perspective as a user, they didn't appear to be doing anything useful in the first place.
I'm sorry if that comes across as a particularly savage take but Atlassian have wilfully been churning out absolute garbage for at least 15 years now (there was a time, in around 2006/7, when I thought JIRA was quite good - genuinely) and their products have made me miserable throughout a good chunk of my career, so my sympathy is pretty limited. If they can be bothered to make the products better, faster, more usable, and remove friction ruthlessly at every turn in their workflows, then I might well change my point of view.