I don't think his statement is true though. If https://www.reddit.com/r/linux_gaming/comments/1ce7z19/gaming_on_linux_ep131_ntsync_vs_fsync_nobara_39/l1ho8od/ is not manipulated in any way, games with lots of these calls still get big improvements with ntsync over fsync (about 30% in this particular case, which is a massive boost). So while nobody can rule out that his statement may be true on average or in general, there are still cases where ntsync offers a tangible advantage – be it improved FPS or the fact that the game runs at all.

Edit: in the video that the thread is about, fsync didn't beat ntsync in a single one (or I missed it when jumping through it). In the best one, they were exactly tied. Sure, the difference wasn't really big, but again there are titles not working with fsync.

However, I want to stress that I'm not trying to talk about fsync. It's a good solution that significantly improved performance. But ntsync is, from everything I've seen, almost always better; how much depends on the case, and it never seems to be worse.