The previous owner of the pool that came with my house would be, in my mind, the "average" pool owner. He went to the pool store about once a month and bought about 60 bucks worth of supplies, including an OTO test kit, some cal-hypo shock, and some Trichlor tablets. I'd say he's a common pool owner, I think a lot of normal folks don't bother with the algaecide unless they run into issues, with how expense the stuff is. And the pool looked great when I got it, very sparkly clean and pleasant to swim in.
Even if you'll grant that the average pool owner uses weekly algaecide to prevent the inevitable CYA-induced algae bloom (which I rather doubt, I'll bet most people wait until the algae bloom actually HAPPENS, but I don't have a lot of anecdotal evidence either way) I don't understand why most pools....work, for lack of a better word. Here's the parts that confuse me:
A) I've never seen anyone mention any kind of upper CYA limit where maybe it stops accumulating. The pool I inherited had a CYA level of somewhere between 150 and 200. I'm not great at reading the test, and the dilution method probably messes up the results somewhat, but still, this guy had been using 3-4 trichlor pucks at a time for YEARS. And this is in AZ, the pool never got drained for a closing. The guy would just try to make sure he was maxing out the OTO meter and be on his merry way, the entire year. It's a backwashed sand filter, so I'm sure that helped some, but we're talking a 1-2% drain MAYBE, done once a month or so.
So if the average CYA puck introduces about 10 ppm chlorine and maybe 6ppm CYA, why wasn't the CYA like 500 or something? The chlorine was getting burned off by the sun, but the CYA kind of maxed out apparently and just kind of found a place it liked despite the continual addition of more CYA, as far as I can see.
When I was googling "High CYA" after I inherited the pool, I saw plenty of people complaining of levels of about 100-150 or so, but no one really mentioned getting much higher than that. Even just in 1 pool season, if people go through maybe 40 Trichlor pucks (I have no idea what the average person's consumption is, but just one puck eroding at a time wouldn't be putting in enough chlorine to keep the FC level correct, so I'd assume most people use at least 2, but I could be wrong of course), just that, right there, should be giving people a CYA level of about well above 200. Even people who close their pools with a partial drain don't completely empty the pool, so the cycle doesn't start at 0 next season.
B) How is it that nobody really knows about the CYA/chlorine relationship? This is a niche site, like I said, I consider the average pool owner about as savvy as the average computer user. They don't know or care what the difference between SATA II and SATA III is, they just listen to the Best Buy guy suggest a computer and they buy it. (maybe I'm being massively dismissive of how educated most pool owners are) Everyone says the pool store folks don't know about (or choose not to mention) the CYA stuff, so if just dumping in pounds of stabilized chlorine over the months is an inevitable problem waiting to happen, why are most pools basically okay (as in, not a green mess)? Are most people's pools just massively overstablized, and they keep the algae problems at bay with Polyquat 60 forever? I can't even FIND algaecide at some places when I'm shopping, but even the local bodegas have trichlor pucks. If algaecide is basically just as important as chlorine because of everyone having too much CYA, you would think it'd be a more prevalent item. Basically with how much it can mess stuff up, I'd just figure more people would understand what CYA is and what it does.
Sorry, this was a long and rambling post, but I think you get the overall idea. I don't think my pool looks or feels any BETTER than it did when the prior owner had it. Granted, I spend a lot less than he did, but if everything I've learned about CYA and pool store chemicals is right, the pool should've turned int a disaster at least once a year or so when he was in charge of it, and it didn't.