Does it even matter when you sign your name on the digital device when making a purchase with a credit card?

A few months ago, I was very angry about something, but I was out getting groceries and in a spurt of rage I signed ‘Fuck you!’ on the pad. It said the signature was accepted…...So then the other day I signed ‘Hello’ with a smiley face and that was also approved.

So does that signature pad even matter? What is it really for?