New to the site but loving it so far. I have a huge backlog. I'd love to be able to sort my collection by the date the games were released so I can keep track of what to play next

Since the vast majority of games in the database don't have release date info yet (though it's always being worked on and updated) this feature would be of extremely limited use if implemented now since most results would return a null value for release date.

As @dhobo mentioned, we're lacking this data for a large portion of the database (especially digital-only games), but adding release date (along with other game metadata) to the Collection page is on my list for the future.