The flaw in WCD's argument is that lots of great QB's in the 60's, 70's and 80's weren't particularly physical. Fran Tarkenton. Roger Staubach. Daryl Lamonica. Phil Simms. Boomer. Joe Namath (talk about fragile!) Doug Flutie. Ken Stabler. None of them any tougher than TB12.
In fact, I think the list of successful non-physical QB's from that period is as long as the list of brutes, In the brute category, I'd include: Elway, Aikman, Jim McMahon, Jim Plunkett, Kurt Warner, Brett Favre.
Unless you go back to the days of Otto Graham, Johnny Unitas and George Blanda, I don't think the ratio of "tough" vs. "finesse" QB's isa much different from today. For example, I'm not a fan of his, but I think Ben Roethlisberger is twice as tough as Montana ever was.
Besides, all signs point to Brady still playing into his 40's, which is its own special form of toughness.