Pyke has been at a 48-50% winrate across all ELOs. He's not even the number 1 ranked support in the game, that title goes to Thresh.
1 as a damage sponge. He can just take your poke,then back off and regen . Which means that if you don't secure a kill you just wasted a lot of your resources.
Poke his ADC, not him. He lacks any sort of external heals or shields, meaning his ADC is vulnerable all throughout laning phase.
2 securing kills hooking you and keeping you in place so that you die
I mean, yeah. This kind of goes for any support I guess.
However, that doesn't mean Pyke is without his own counters. As mentioned above you can easily poke out his ADC but dashes and heals counter him heavily. Sona and Soraka have no problem invalidating his ultimate and presence in teamfights. Dodge his ult and his usefulness is cut down heavily.
3 denying CS all he has to do is get into position and that forces you to move away from getting CS because if he hooks you its a kill, this is more true at level 6 when he gets his ult.
This is the case with all hook supports. Blitzcrank, Thresh, Nautilus, Pyke, and even Alistar (to an extent) can easily zone out your bot lane just based on their presence alone. In fact, I would say Pyke is actually the worst at this because his abilities are very telegraphed and the majority of marksmen should have no problem escaping his delayed combos.
) can deny you CS by walking up close to scare you