Because any reasoning behind drinking is seen as an excuse to be a drunk.
You're self medicating with alcohol. That's not the worst thing in the world. It helps you. It sounds almost like a miracle drug for you. I don't see why you'd rather switch to benzos.
Just understand, alcohol is addictive and tolerance can be built up, so you're dancing with the devil and you'd better adhere to a set of rules. One drink a day (or every 4 hours or whatever the schedule is to keep you from losing your mind), period, and if it stops working as well, quit for a week or two, anxiety be damned. Also, understand that you're making a trade off. There are health impacts of alcohol, and you're accepting those as worthwhile for the benefit you get. Look into it, be honest with yourself, and determine whether you're happy with the trade off or not.
People self medicate with all kinds of things, and people take things recreationally. I'm personally not a fan of recreational drug use, I use compounds when they're useful, and I make sure I understand them, dangers and all. I do a good slightly excessive drinking session once every couple of months or so to clear built up stress from my head. I might have a drink or two once in a while between those if I'm having a particularly stressful day. I take an opioid (legal, believe it or not) sometimes for acute extreme pain, and won't take it more than two days in a row, pain be damned, so I time it for maximum impact. I drink a cup of coffee a day, just one, that's it, to medicate for migraines. I could probably get away with once every other day, but it's too delicious and not particularly strongly habit forming. I do manage a nicotine addiction, but nicotine (not cigarettes) does increase my clarity of mind when solving problems, so I don't really mind it.
Everybody self medicates, the distinction is what's socially acceptable, and honestly what's socially acceptable is not taking the reigns of your own health and instead putting it in the hands of professionals. And you're supposed to take drugs that have existed for a decade instead of ones that have existed for thousands of years. You're supposed to outsource understanding how they affect you to professionals. We have an opioid crisis because of that, as part of a larger unhealthy relationship with drugs in general as a society. I'd say, stay clear headed, use your better judgment, and just do what works for you. The taboo is misplaced and detrimental to our society. Don't drink too much or switch to benzos and you'll probably be fine.