Isn't League of Legends just a WarCraft 3 without gathering resources, building buildings and training army? Basically just hero units fighting akwardly.
For some history, the original DOTA was a custom map in Warcraft 3. It pretty much defined the moba genre. From there lots of clones were created, and eventually some were made into full games. League of Legends is one of those, and became the most popular. So yes, they're all just Warcraft 3 with only the hero parts.