Re: Every user?
I agree with you and you are correct, but the article seems to imply that IP address is the basis for a search. Perhaps a current IP as opposed to historic? Not really a favourable situation :)
FWIW - I used to work at a telco which would occasionally get warrants from the AFP to ask who is username x or who used IP address y at a given time as described. DHCP was not in use as the bulk of the customers were DSL which uses PPP/L2TP and fixed IPs (which of course don't need to be logged) for the bulk of other services, but the principal is the same.