I think you're understating Dota's influence. Its predecessors were tiny blips in comparison. Dota professionalized the genre and had huge popularity, which was only limited by Blizzard's poor infrastructure and support. Many people wondered why Blizzard didn't embrace the mod that far surpassed the popularity of its own games (the answer is probably "WoW"). League of legends took it to the next level with the infrastructure the genre needed.