There’s never a reason to go into a store blind. If you don’t have a plan, you’re at the mercy of the shopkeepers who know you and your preferences better than you do.
If you go to a grocery store and don’t know what you’re going to buy, you’ll buy too much.
If you go to a clothing store without a budget, you’ll spend more than you would have thought beforehand.
If you online shop for nothing in particular, you’ll end up buying something completely unexpected.
None of these things are inherently bad or mistaken. It’s just a question of whether you would do it again if you could go back in time.