Doing something that hasn't been done before in a major genre of games isn't conventional just because the idea has existed before. That's not what unconventional means. Unconventional means "not based on or conforming to what is generally done". Just because something has existed before does not mean it is "generally done". There is plenty of shit in this game which has shown up rarely and as a very minor part of past designs, and wasn't made into a major mechanic until being added to League. That's unconventional. Doing things differently even through unusual innovations on past ideas is the core of what unconventional is.
There is no point in going with the definition of "if it's ever been done in MMOs or RTS before than it isn't unconventional". All that means is that no MOBA has ever had any unconventional ideas at all. Every idea in any MOBA was done before. Techies, Murky, Abathur, whatever. All done. It's an unrealistic and nondescriptive standard, so who gives a fuck if we meet it? The term doesn't matter to MOBAs at all. It certainly doesn't describe the concept OP was trying to get across in his post.