Celery is used because it’s cheap…and it’s bitter balancing onions and other cheap stock items that tend to be sweet. A stock shouldn’t be sweet or bitter because it’s something you “work up”.

“Everybody” doesn’t use it tho. Some stocks are “garbage can” stocks, using whatever unservable scraps that come from food preparation…others are from ingredients purchased to make the stock like a Mirpoix (the most common stock base that uses celery).

There are lots of people like you that say celery ruins stock…there are many others that say bell peppers ruin stock…but then there are core stocks made from bell peppers.

Just do what tastes good.