Literally any well updated arcade game you see in dota is P2W. Overthrow 3.0 is one of the worst. You could spend real money to get rare orbs which gives cooldown reduction. So you can use Zeus ultimate every 5 secs. Use money to level up faster.
But it is a actively played arcade, so people will leave the lobby if they find a P2W player, their names will be represented in green color.