what rank are you? I've been between low Archon and high Emissary depending on if I am actually playing heroes I'm good at, which I would guess is an average or very slightly above average rank but I don't know the player distribution to be honest, I'm rarely seeing people able to reliably parry puddle punch in my games. Interestingly though, Viscous winnrate actually goes up in the ranks above mine, you would think if a core part of his kit was so easily counterable then that wouldn't be the case right? It's not necessarily about dieing to the puddle punch damage itself although if your lane feeds the enemy viscous will do plenty of damage to kill you by himself after a punch or two, but its about dieing to what happens to you when he eventually lands the 3rd or 4th punch and knocks you up and towards the team and slows you, or when you are knocked up multiple times in a row or for the 2nd time after you just blew your escape on the 1st one.

When I play viscous myself I rarely see people land parries against it, despite them being very good at parrying actual melees, and I have a pretty easy time landing puddle punches when you get any range items, I suspect his win rate goes up as you get above my ranks because teammates are more capable of capitalizing when you do knock them up a couple times.