Because our trusty TSA has put out a directive (prior to this all happening), if your airline does not fly into/out of that airport, you must get a boarding pass from the ticket counter.

BTW-This was going on in BOS , and in FLL (if your company does not fly out of that TERMINAL even!) before the directive.
I tried to "bypass" this 3 years ago, and the TSA agent noticed the company I work for did not fly out of BOS (we do starting TUE. though), so I had to go back and get a boarding pass. And then what do you think happens? I got the old "SSS" next to my name. Would happen most of the time unless the gate agent "knew" me and somehow by passed that. Anyway...

And then have to sit and wait to see if you get on.
They ARE sceening PAX at the gates (yes AFTER they ALREADY have been screened), so you might get a "smart" TSA (oxymoron) agent who notices you not boarding, with a boarding pass in hand, and THEN you're in big DooDOO!!!