Two problems with it were that 1. often setup boilerplate overshadowed the actual essence of the documentation and 2. people abused them for e2e testing making for unreasonable reading (and slow testsuite runs).
plenty of tools to turn that into html if you want
confluence is bloated an unweildy
Jira done well is actually nice
Confluence is slow but pretty simple, standard wiki otherwise. Obviously, if I had a choice, it'd be nothing Atlassian.
git+markdown limits editing to developers only.
The question was about developer documentation, so non-developers was put to the side in my answer. We are also now in the agentic age, so git + markdown is operationally much more aligned with the primary doc producer and consumer. We are more managers and editors these days.
GitHub Issues today seem bloated too, so perhaps your frame of reference has moved backwards while you weren't looking and suddenly Jira is fast?
Jira is a highly customizable beast, it does matter how your Jira wizard sets things up