poison probably got removed because after RS, a lot of random points in the game are littered with poison point pokemon. poison was introduced in gen 1, when the threat of poison in early routes was a 1-in-5, or 1-in-3 chance off poison sting, which was actually more like a 1-in-10 or 1-in-6 or higher, since the random weedle or wurmple was just as likely to hit you with string shot than poison sting
many players are likely to get experience an overworld poison KO at least once or twice, but from that experience learn to quickly avoid it, levelling up the pokemon on other pokemon – eg caterpie instead of weedle, until you can 1 or 2HKO weedle, and then farm off that pokemon for exp as well. your odds of being poisoned fall off significantly
however, add in poison point, and in addition to the >1-in-6 of the CPU choosing poison point and it processing poison, you're now probably attacking the pokemon with a physical move (tackle or scratch) at least one or two turns. the odds are now becoming that it'll be the case more often than not that each encounter you have with a weedle or wurmple or whatever fucking bug it is will leave you poisoned
poison point is a nifty ability for competitive, but it's terrible for the single player campaign, because even when you do well – knock out the pokemon, well done! – you're probably going to be punished for doing it. does it fit the flavor? kind of, but it's too lethal and threatening in the early game, and annoyingly punishing at other arbitrary points in the game. poison is a good condition and overworld poison is an interesting added consequence, but poison point makes it less of 'threatening consequence for playing bad' and 'threatening consequence for KOing a weedle' which is incoherent. like a lot of abilities, it makes the single player campaign shittier. instead of nerfing abilities, which would be lame for competitive, they decided to nerf the status instead.
dumb, abilities suck
