Yeah that is what they write for the terms. In practice though they have never enforced the 1TB/user clause, can't find any references to them doing that ever. Many people claim to have many terabytes with no enforcement on the user clause, myself included at 13TB currently with 1 user for just under a year so far. Apparently it has been this way for years.

Effectively you get unlimited storage for $12 + taxes/month.

It's a pretty smoking deal if you don't mind the (seemingly minuscule) chance that one day they'll ask for more money or pull the plug. In my use case all the data is easily retrieved again so it would only be a minor inconvenience.