It is all about the Benjamins - the Pats apparently have their designated resale service (TeamExchange) that any reseller needs to go through. So they sued StubHub and ticketholders who would not play Kraft's game by Kraft's rules.
Just before Thanksgiving, the New England Patriots sued online ticket reseller StubHub.com, a former season ticket holder and former wait list member and other season ticket holders for reselling their tickets online
The Complaint alleges that StubHub and the sellers interfere with the Patriots' advantageous relations with its fan base, misappropriate the Patriots' name and violate Massachusetts law.
The Stelers also have a designated resale service but I do not think the Rooneys are seeking to get the names and revoke the ticket licenses of anyone who goes through StubHub (and Steelers tickets certainly are on there).
With the Internet scalping works a lot more efficiently and the teams want their cut - some work with StubHub and other ticket brokers to split the take, as stated in this article on the case:
In most other states, fans are allowed to resell tickets for any price and professional sports teams have jumped into the business to earn money by facilitating the resales.
The Phoenix Suns basketball team and the San Francisco Giants baseball team are two teams that operate marketplaces where season ticket holders can resell tickets at any price, with the teams taking a percentage of each sale. Major League Baseball this summer signed a deal with StubHub making the San Francisco company the league's official marketplace for ticket resales.
Not surprisingly, the Kraft/Belicheat mindset of "what's mine is mine and what's yours is negotiable" results in a different approach.