You beat me to writing the exact post I was about to write.
Completely mind blowingly unacceptable maintenance. When my pool goes green, its because I was out of town for 2 weeks and didn't pay anyone to check it and forgot to top off the chlorinator, but sometimes I have more impotant things to handle than whether my pool is readily swimmable.
As far as cyanuric acid is concerned, I was blown away when i discovered the relationshi between CYA, chlorine, and the effect of sunlight on the pool. At 50ppm CYA, you need like 3-5 ppm chlorine to keep the pool clean, and sunlight prevents the chlorine from breaking down as fast, but it makes shocking it very expensive if you forget your pool for a week and it turns green.
Meanwhile, at a CYA level of 0, it might only take .25 to .5 ppm to keep it clean and as little as 1-2 to shock a green pool, but with no CYA, sunlight will destroy the chlorine instantly.
In the middle levels of 10-30 CYA, you don't need as a high of a chlorine reading, and sun doesn't destroy the chlorine instantly, but you still need to watch it, BUT you can also dose less chlorine when you do.
Its when the CYA gets up to like 100 that even shocking the pool becomes difficult because you need like 20ppm and even in a 24' 4' deep above ground, thats like 2 whole gallons of shock, and you might need to do that more than once. Gets expensive quick... easier just to keep the chlorine and cya levels lower.