For the record, they don't need to fix the cap per say, they just need to fix how it's been done. The problem isn't the cap itself, its that they don't know how to program the game with a proper cap. So rather than doing a hard cap, which would make it so that people could never get over 100mil regardless of what damage they do, they just use the % of damage as a controller, so that 1% = 1mil. 10% = 10mil etc. If they took the damage that is actually displayed at the end of a round (which for the 6bil boss, is approximately 5 times more than the 1.6bil boss) and allowed you to accumulate at that rate until you hit 100mil, at which point any more damage that you did wouldn't result in more coin for you, I don't think we'd be having this discussion, and that would be proper coding. Unfortunately, their programmers went the easy way out, rather than programming properly.
So whether it's been talked to death or not, it's actually still a BUG. Because the return does not reflect what is shown on the per round basis. It's using the % of damage instead.