Yes there is deviation, however I seldom get a massive (30 -40 yard) variance.If I do it has often been my fault (tired and not following a pre shot routine etc).
But all that said, I get as much if not more variation in real golf (and I used to play off a lowish handicap), so those who complain are really just replicating the real thing.
Frustrating? You bet but it is just a game, and overall, a damned fine one. I would like real competition as it would only raise the bar for both companies.
Yes, there are a lot of issues on WGT, but for me, variation is not a major one.
Looking at players who have complained regarding constant massive variation (in a certain period), past and present, the common denominator is the scoring has been constant regardless of the period.
Finally, why is it many players also never complain when a rank, badly missed ding ends up 3 feet from the hole? Short memories me thinks!