Nasus and Veigar in Pro Play?

So recently, I started noticing how in pro play, everyone has super good cs and farm numbers compared to solo queue. This means they are nearing end game by about 35~ minutes, which is actually fairly common for the lcs right now. That got me thinking, since the game is so accelerated, why aren't infinitely stacking champions like Nasus and Veigar ever picked? Pros can easily reach 200+ cs by around 20-minute mark, the dream scenario for nasus.

The most obvious reason is the fact that they can easily be set behind and countered, but then wouldn't that also mean less jungle presence for the other side of the map? If you're the enemy jungle, who would you rather gank, the hypercarry adc, or the free farming nasus? It's a tough decision, and we've seen it work for good top laners who can survive on their own, especially against passive laners. Ssumday has done it in the lcs awhile back, and KZ also did it against Fnatic at worlds. It works as a situational last pick against passive laners, or as a way to force the enemy jungle to come to your lane or risk having a farmed up nasus late game.