Volibear DPS late game is garbage. Mid and early game it's good and is what makes him a threat damage wise.
Who gives cares if liandries is better on him now.
Cho'Gath has a 45% winrate so yeah, those buffs will help him do better. Also it's not even that big of a deal. Poppy gets 16%max health on her Q and doesn't require any scaling or nothing. Yorick gets 10% every 2s with Maiden and only needs levels. Mundo gets 25% current health and you get permaslowed.
They're just buffs to help him before his rework and the buffs are fine.
The only way Cho'Gath is gonna reach his targets is if flash is off CD or if he lands a Q. Even than he can get CC'd himself and is a huge target which makes him easy to hit.