There are presumptions that you were of sound mind and it was you. Unsurprisingly, courts are full of weasely, pro se people who waste everybody’s time because they, very much incorrectly, think that they can get out of agreements by going into court and making the brilliant, one of a kind argument of “but your honor, they can’t prove that I clicked it. I was hacked/someone else must have logged in as me!” People do this all the time and they lose all the time. Modern commerce literally would not function without these presumptions.

Edit: also, fwiw, there are exceptions but generally speaking verbal agreements were and still are very much valid, whether written or not, unless the agreement fell into certain categories (e.g., sale of land). Same deal, annoying people think they can outsmart the system by just saying “but your honor, none of this was ever put to paper.” They are, with important exceptions, also generally wrong.