The English Wikipedia alone has hundreds of thousands of items to fix - missing references, misspellings, etc. The problems are nicely sorted at https://en.m.wikipedia.org/wiki/Category:Wikipedia_backlog . There are millions of other things to fix in other projects. So quality is getting higher in many ways, but the amount of stuff to fix is still enormous.

What we don't have is an easy way for new people to start eliminating items from the backlogs. The Wikidata games are a nice step in the right direction, but their appeal to new participants is non-existent.