Most drugs are not strongly physically addictive. Most drggs have short risk-free withdrawal times. Alcohol is rare in being a drug that has a risky withdrawal that needs medical supervision - and even that's for people who are on the very heavy end of the drinkijg spectrum. (A litre of spirits with an ABV of 40% per day is what you need to get a medically supervised withdrawal in England. That's about 33 US fluid ounces per day). People can be having serious problems with drink and mot reach that threshold.

Saying "you can just quit" ignores the severe trouble that a few people find themselves in with things that are not physically addicting.

Telling someone with a gambling addiction that they could just stop is an over-simplification. It's such an over-simplification that it's dumb, and thus it's not surprising a few people felt it needed a downvote.