You're right, of course. Getting into the playoffs isn't easy, unless the conference is so weak (like the NFC East in recent years) where .500 might be enough. It is magical for a lot of teams. Ask any Giants fan who endured the 2011 season, when they lost 5 of 6 games late in the season and things appeared hopeless, only to do the seemingly impossible.
Not really meaning to downplay how difficult it is. Just saying that I would expect Pittsburgh to be a lot more consistent than they have been, given the quality of players who've cycled through there over that time. Then again, during that same time, Marvin Lewis has (mostly) turned a fledgling franchise around in Cincy and made them competitive again.
Sneak spoke to something very valid about winning on the cheap. New England, for years, has used free agency better than any other organization in the history of the NFL. They take the rejects from other teams and not only find a place for them, but develop them into incredibly reliable role players. I agree - don't know why more teams don't spend more money on good coaching and scouting, spending less money on over-hyped, underperforming talent, and finding those players who fit their need.
Maybe because being that competent, from the owner, to the GM, all the way down to the coaches, is something that very few organizations have a schematic for. You don't build a dynasty without those pieces fully intact, because quite frankly most owners don't know the first thing about putting together a winning team. It is very much a top-down process.