I can't say I share exactly this experience, but I did have some experiences of old that I miss.
The only non-MMO I ever played multiplayer prior to ~2013 was Age of Mythology. I never played ranked or competitive, but I did play a shit tonne of fun custom scenarios. Escape maps. Arenas. One really fun Helm's Deep map that would always slow to a crawl once a larger number of units hit the field. I'd browse through the open lobbies and find something that struck my fancy, or create my own lobby and wait for people to join. Hours spent browsing the Age of Mythology Heaven forums for scenarios and reading people talk about them.
I do mind miss those custom scenarios. The new Age of Mythology: Retold feels much more focused on the ranked mode. Which I do also really enjoy. But there doesn't seem the same culture of custom scenarios that there was back in the day.