User blog comment:YurdleTheTurtle/LoL & DotA 2 - AMA and Information Blog/@comment-187.39.188.3-20121121213129/@comment-4861674-20121122042724

It goes back to Riot's philosophies that I hopefully outlined correctly and clearly. For them, it all comes down to simplicity without sacrificing fun. Clarity is of utmost priority for them and quite frankly a hero like Invoker wouldn't work in LoL because of the 'burden of knowledge' and other problems he would bring in Riot's eyes.

This goes back to the points I mentioned in my blog though. DotA certainly does have a higher learning curve but the rewards can be greater simply due to the greater challenge. However, Riot sees this more of an issue of "Might be fun for some, but for vast majority, problematic".

At least, that's what I believe is how they think, according to what I've absorbed from hanging out on the forums.