The level leader board is pretty useless in my opinion,since almost nobody actually post there(because of the fact that those bosses take a long way to get to) And nobody will be willing to spend that much time on a clicker game.

Like,level 100 already took 9 hrs to get to :/

Yeah it's crazy. If I had kept going after my 200 run it wouldn't have been much longer to 300 and even less to 400, and so on. Progress tends to speed up, 200 is the big hump. I personally don't find it useless, as it's the least possible arbitrary thing you can achieve in the game. Every number on the full-game leaderboard is made up by runners, whereas the game signifies these 10 specific bosses as significant/important.

I don't see why this is an issue anyways. There are a lot of games with long runs.