These games have infinite replay value and people like them. That's all a top ranking game is. Many have tried to replicate these successes and failed (in recent memory, Concord). There have been a huge number of good games coming out too. But they're not somthing you put 2,000 hours into with your friends.

There'a a big element of the snowball effect too. Big games attract more players than small games. Esports are a lot like normal sports in that regard. People make new sports pretty often but Football, Basketball, Baseball etc have been around for 100+ years so they have large communities and social relevance. If I asked my buds to go out for a match of "whipple stick", my new favorite sport, they'd just laugh at me.

On the other hand, new games CAN become huge if they're built well enough. A few of the top 10 were released less than 10 years ago, which says a lot about how these "main games" DO change over time. I think Deadlock will get up there after a few years of polishing.