I disagree.
I do agree that a true 3-4 Nose Tackle is a rare man. Tough to find those. However, the ends and LBers are much, MUCH easier to find. You don't need spectacular, you need competent.
In the 4-3, there are two spots that are tough to nail down. Those are MLB and Rush End. The attributes needed to be an above-average rush end in a 4-3 are EXTREMELY hard to find, and you really want 2 of them. I think that it was the Tuna who said that he could find 10 good 3-4 LBers to every 1 good 4-3 end because guys that are 290 pounds, strong as an ox, and as fast as a deer are hard to find. As for MLB, those in a 4-3 are your big, strong, fast run stuffers that can hit any gap with authority. Those have become RARE indeed. So you are searching for 3 rare dudes for a 4-3 and 1 rare dude for a 3-4. Every now and then, you stumble upon a HOFer. Your Reggie White's. Your Brian Urlacher's. Your Lawrence Taylor's. Your Vince Wilfork's.
The reason that the Cheatriots switched was Wilfork. If you recall, his contract expired after 2009 and he wanted, publicly, to get out. He eventually was resigned to a 4 year deal that was really a 2 year deal with an out for the team. So 2011, when the Cheats switched to a 4-3, was Wilfork's last "good" contract year for the team and they had just signed Albert Haynesworth too, so they had a glut of big bodies that year. Haynesworth flamed out spectacularly and the Cheats kept Wilfork all four years of that contract, but he liked playing in a position other than NT and it showed. He was 1st team All-Pro in 2012 as a DT, not a NT. The Cheats even sometimes played Vince EFFEN Wilfork at DE for cryin out loud, and it was NOT because he was the fastest guy they could get on the field. LOL
The beauty of the 3-4 is that the offense KNOWS that there are going to be at least four men coming on every play. But they only know 3 of them. To play a 3-4 correctly, you must have LBers that are equally capable rushing the passer and dropping into coverage, so that ANY one of them could possibly be the fourth rusher. When we last ran the 3-4, everyone and I mean EVERYONE, knew that when the chips were pushed into the middle of the table, Demarcus Ware was going to be the fourth rusher. No deception at all.
This is why taking OLB in the top 12 is a Fool's Errand unless you have TWO of them, or LT; who was a transcendent talent.
What made the Stealers so great at the 3-4 was that, on any given play even if the season were on the line, no one on the opposing offense knew for certain who the fourth rusher was going to be. They had total deception on every snap.
Anyway, I've droned on too long. In short, I disagree.