T he line is well known but usually reserved for blitz or skittles play. I think the stats given above pretty well show why. But just to add ... look at blacks position from a strategic perspective. Often in the mainline Winawer, such as the poisoned pawn lines, BL will castle Queenside. But here with WT having an open a-file with Rook already on it, and a b-pawn to ram into the position should BL o-o-o ... well he probably doesnt want to o-o-o then~!
However, the alternative of o-o simply plays into WT's natural field of play, since that is where WT has his space advantage, has pieces that will aim at the ...o-o, and can play vs ...0-0 with pieces andor pawns.
So those of you who really know the French, might point out; "Okay, but is it not true that BL can often find a home for his King on d7 or d8 in the French that is quite secure!? Yes ... but that is lines where the center is fixed and closed, and definately not so here where WT has two c-pawns with which to attack the d5 pawn and probably open the d-file. Additionally he has a great piece outpost at d4 until he does open the d. Plus an advanceable f-pawn to lever vs e6.
With the BL K-position so questionable, we might ask ... well can he not "get to WT" first? To WT's King if it is o-o for EG? Well ... does it LOOK like BL can?? :) I have some extreme doubts on that one.
Finally add to it that WT can Choose his field of play. Q-side, K-side, or Center. A BL defender will generally not want to grant such generous options to the WT player. This point alone would cast a shadow on seeing it in GM play. But the Question of King safety for BL will "turn out the lights" on that totally, imo.
Nobody familiar with the french would play 5. cxd4