Like to chime in, we’ve seen these drop in on a shop that technically doesn’t even have customer accounts (disabled in settings, but that doesn’t stop the registration URL from being accessible).
What is… the point though? I can see for spam contact form submissions how 1 in a million reacts to these “great offers” for better marketing and whatnot, but as a customer, all you can do is… be seen? And see your orders? (Weirdly enough, one of the “customers” even had a note).