One of the things that differentiated DOTA 2 from League of Legends was that it felt a bit like an exclusive club. Players had to jump through a whole bunch of hoops, getting invites from friends, signing up to get game keys, so on and so forth. Granted, it wasn’t that hard to do, but it was complicated enough to turn some people off.
Well, all of those complications are a thing of the past, as DOTA 2 has completely dropped their sign-up requirements. Now, anyone can join simply by going to the game’s Steam store page and choosing to download it. Hooray!
Valve has been making several improvements to DOTA 2 over the years, specifically regarding the game’s network infrastructure. Perhaps the game is finally able to support open signups. DOTA 2 currently hosts 6.5 million unique players, whereas it’s chief competitor, League of Legends hosts 32 million.
Source: DOTA2 Store Page