No one is completely prevented from leveling things. League store provides all the relevant gear, and everyone gets trainers free every day, plus event rewards and milestones. It just takes a long time, but so does getting a new Sclass toon.
But that’s not really the point. My point is that Scopely know exactly how many resources they hand out, and everything is balanced against that. If they didn’t want there to be a shortage, they could have made upgrading cost less gear. The economy is not behind, from their perspective, it’s exactly how they want it.