They certainly don't require it but it tends to be used in other transactions where SEC is going to hang you for example.

And my memory of Florida law (when I was signing an apartment rental contract 4 years ago) was that any electronic signature agreed to by the contracting parties was valid. So I simply typed my name in the contract, emailed it to my landlord, and we were done.

Of course, I also used https:/.opentimestamps.org to store the hash of our contract on bitcoin's block chain, because that way we both had proof that the contract existed in a certain form on that date. (I never needed that proof, because he was a good landlord, and I paid rent on time.)

While probably enough to prove it existed, you'd probably need to pay a lot for an expert witness to testify to "hash of file on blockchain means it existed" if you did have to go to court over the existence of the contract.