So, I'm currently in a dungeon. I'm at area 16200 as I type this sentence. Still going, no signs of slowing. Despite that progression, my dungeon points are only 2750 and my coin are 75, and have been for quite a while. I didn't even know there WAS a cap, but I guess there is.

Beyond that, before I hit the caps, I had noticed that even by around 2600 points, the rate was still barely 1 point per area. At some point (I've yet to calculate), even without the cap, finishing a run and resetting before reaching the end is more profitable then pushing as far as possible. If the rate of point acquisition doesn't keep scaling, it quickly becomes a juggling act of acquisition versus time that skews more and more toward woefully not worth it.

WITH the cap and the stagnating rate growth, only going up to the cap MIGHT be worth it (Again, haven't done the math), but I predict the time:payout ratio would be very close.

Main points: There's a cap, and rate of growth tapers out until deep progression is unrewarding.