I mean the reason was entirely security theater.

Locking, reinforced cabin doors and air marshals prevent another 9/11, banning toothpaste does not.

There's zero evidence the TSA has stopped a single terror attack, and on top of that they fail their own internal red team tests 95% of the time

Unless you're bringing more than a week of outfits or you need to bring so much stuff that you can't fit it in a carry on, why would anyone choose to pay the extra money to check a bag

The entire agency exists for no reason my dude