Discord I get, at least from a community or network effect, but Bitbucket? I can’t figure out why anyone but a CTO looking to save a buck would prefer Bitbucket.
We use BitBucket where I work. Due to certain export regulations it's simpler for us to keep as many services as possible on-prem if they're going to contain any of our intellectual property, so BitBucket Server it is. There are other options of course, but all of the cloud solutions were off the table.
I wouldn't know, the choice was made years before I joined the company, and I haven't come across anyone who told me what considerations went in back then.
External AI are banned, local or otherwise on-prem models are allowed. We're currently experimenting with some kind of llama instance running on one of our servers, but I personally don't use it much.