Ooh ooh I know! Multiple hard pulls on your credit can indicate that you’re looking to borrow a lot of money. Why do you need all that money? Are you going to be able to pay it back? Why can’t you solve your problems with your own money? Etc.
Multiple hard pulls can also indicate that you tried to borrow money (or do something else finance-related) and the first financial institutions you tried turned you down. Which is also bad.