Could this be used as a sort of makeshift stadia rangefinding system?

Mind you, it does nothing that properly calibrate mil-dots don’t do better, but it may be that they perceive mil-dots carry a certain politically unfortunate connotation (i.e., they are for range estimation to facilitate antipersonnel work at unknown ranges, probably in access of 500m) whereas multiple holdover marks are just, ya know, holdover marks. For shooting at deer. And paper targets. And other legitimate sporting purposes.

You can use mildots for holdover too, though they are perhaps a bit coarse for this at long range.