I agree with the idea, but maybe level 10 would be too high. I think even level 3 or 4 would be acceptable. This would give new players a couple tutorials and a bot game or two before getting into a game. That way, experienced MOBA players who can legitimately come in and play acceptably well wouldn't be frustrated with vs AI which can be boring to competitive types, but still at least require people to have seen the basic stuff, like how to know which lane to go to.
I can't even remember how many times I've had players who had no idea what lane they were supposed to be in, but I can remember creating a league of legends account as an experienced MOBA player and being annoyed by limited game modes. The trick will be finding an acceptable balance.
If the dev team can implement this well, I believe it would make for a much better retention rate for new players, since those new to MOBAs wouldn't get both destroyed AND flamed, and experienced players wouldn't be bored into alt-F4ing and switching to their old favorite.