Self-hosting JIRA and Confluence was a double edged sword:

Done badly it meant you suffocated the application server with too little resources giving dreaded "super slow JIRA" effect.

Done well it meant you didn't have to deal with Atlassian underprovisioning resources in the cloud or having rigid maintenance times that didn't fit with your company needs.

I’ve never seen or worked with a company using the cloud version of any of their products. I worked at a place with one of the largest bitbucket installs in the world, so they weren’t little shops.

The rise of self-hosted GitLab and GHES suggests that's not true.

Not true. I‘ve been at several companies that self host Jira. With the amount of critical data and processes in Jira, it can be comforting to have it on-prem with no one else being able to access the server.

You can ask Boeing ;)

Joking, I do not think it is the case, BUT I do know that cheap is often more expensive