I agree, but I've gotten less annoyed by it over the years. When I was young it really didn't make sense to me. Money can do literally the same and is way more versatile.

However, now that I'm trying to survive this adulting thing it does start to make more sense, even if I still don't like it. If someone gives me money, it ends up on the big pile of money that's constantly flowing around. Give me 20 euros and it just adds 20 to the number in my bank account, which will eventually end up being used on groceries, bills, mortgage, etc. if you give someone money as a present you don't want this. You don't know what to give the other person ans you want them to choose something nice for themselves. But buying them part of their groceries or a part of their bills isn't exactly a fun gift. You want to "force" them to buy something nice, something that they want to spend money on instead of need to spend money on. A gift card does this.

Then again, giving me physical money would also do this. Or asking me to say when I bought something nice with it. When people gift me money I tend to tell them where it went and that works way better than gift cards imo.