I think the answer is “it depends on your community.”
The Discourse philosophy is that trusted members of the community help curate the space – pick up trash via flags, organize topics and categories via TL3 editing, put up helpful clarifying signs in the Contribute > Site feedback category, etc.
The general idea is that the community helps organize itself. If this isn’t what you want, there are site settings as @falco noted:
trusted users can edit othersAllow users with high trust levels to edit content from other users
That one is specific to editing, so it would disable the TL3 ability to edit topic title and category.