You paint with a very broad brush. We have a vibrant division here, 10-14 teams most sessions. Both 8 and 9 ball nights. (There are two nights of TAP in this room as well, meaning four nights in a row full because of league pool.) People ARE having fun (except for me when I play like a bonehead, sigh) most of us know each other pretty well by now. Is there a social aspect to it, certainly. But people take it seriously enough, and are usually pretty good sports, too.
I make it a point to keep score as much as I can. I'm not a very good player, but I watch all of the players, and have for years. I know who is under-handicapped, for our league. Most folks are pretty close to where they should be. For our league. Comparing one players ability versus others. Once in a while there is someone who is pretty obviously below where he/she should be. I like to make sure to score those folks matches, so all the defensive shots get marked. Yes, many folks don't do that. But its a general, league-wise phenomenon, no matter how many times it gets explained. Meaning its pretty consistent that those keeping score aren't marking defenses when they should, for both teams.
In 95% of these instances, the players aren't trying to pad their innings to sandbag. There are a few folks that I can tell are doing it. But a small number. So its not "rampant" here. Of course, it could be elsewhere. Your mileage may vary.
I enjoy my league nights. Obviously lots of others do too, else why would the APA continue to thrive, given all the bellyaching we see here. It serves its customer base, and serves it well. It sure isn't for everyone. And that's OK. Stop making it out to be awful just cuz it ain't for you. Many pool rooms would be in tough shape without league, APA and others.