Dokuwiki is my go-to tool for internal wikis. Unfortunately it won't help you with the two issues listed above: It's still PHP and there's no conflict resolution to speak of. It also hasn't changed much in two decades.
What it does right is that it's trivial. Trivial to understand, trivial to use, trivial to upgrade, and trivial to write plugins for. These plugins can then suck in data from external systems and CMDBs which is perfect for internal documentation. Mediawiki is designed for another use case and much more complicated.