I honestly despise Confluence. Jira is kind of OK if you don't create overly complex workflow (they will fail) and avoid using it as a documentation tool (it's not versioned, editing tool are lacking, adding content is quite limited, updating content while fighting field is not fun and finding back the last CR related to a feature is hell).
But Confluence is the worst Wiki I've ever used. It's editor is obnoxious, it's so damn slow, you're losing edit whenever anything happen, tagging is quite often random (recently it added an unwanted "my.favorite" tag to page I'm copying), it's search is broken since the beginning, hierarchical view is broken, creating add on requires to be a high level admin and the implementation is horrible... And I've been forced to use Confluence for 10 years now, in multiple company. None was ever good with it. Heck, here people are screaming to go back to Sharepoint.
I've been using Confulence for a long time in all my companies. It's not the best product for sure.
However, regarding:
1) slowness - it's faster selfhosted than their shitty cloud solution
2) editor - one of the best features, not replicated anywhere is their macro collection. I'd prefer markdown, but dynamic object embedded in our specs/documentation is a very useful feature. Also for non-technical people their editor even in current state is easier than other non-WYSIWYG editors for sure.
There is a place for a competitor to Confluence, because the need is still there. Help non-technical people capture and buld documents self-hosted inside your firewall with dynamic elements.
Atlassian's decision to dump the self-hosted version in 2024 will create the niche for all the companies that would want to migrate away. They just got greedy and got too big, went public, founders cached out and now it's the hired managers playground.
They've (recently?) introduced a feature where they disable the editor window in Confluence if the browser even momentarily loses the network connection. On a poor network it's absolutely unusable now.
But Confluence is the worst Wiki I've ever used. It's editor is obnoxious, it's so damn slow, you're losing edit whenever anything happen, tagging is quite often random (recently it added an unwanted "my.favorite" tag to page I'm copying), it's search is broken since the beginning, hierarchical view is broken, creating add on requires to be a high level admin and the implementation is horrible... And I've been forced to use Confluence for 10 years now, in multiple company. None was ever good with it. Heck, here people are screaming to go back to Sharepoint.