I haven't heard anything about the accuracy drop, but if that's true then it's even worse!
As for the "most Kang don't use Power-Up Punch" arguement; PuP is used on 41% of Kang, that's a lot. Sure, there's 59% that aren't using it, but of that 59%, probably about 30% are Fake Out + 3 attacks, and 20% are mixed attackers with Ice Beam. This means that compared to other sets, PuP sets are the most common build. So Kang is losing its most common (and imo best) set. That surely makes it worse.
I'm glad you brought up Secret Power because I forgot about that; it's gone as well. This means Kang is also losing its most common STAB move. Yes, Secret Power overtook Double-Edge last season! The meta has become so hostile to Kang that people are opting for nearly half the damage output just to avoid recoil (para is handy yeah). But the thing that made Secret Power actually usable was, yep you guessed it, getting to +2 with Power-Up Punch.
We can also look at the
leaked Alolan Regional Dex and see what Kang will struggle with now. The first thing that pops out to me is Porygon2, without the threat of PuP and decreased damage output thanks to the P Bond nerf, everyone's favourite duck has become an amazing check now that Double-Edge can no longer 2HKO. Even Hammer Arm will struggle to 2HKO... Skarmory is even better since it doesn't have to worry about PuP + Fire Punch anymore (well at least until bank mons are allowed but they'll be banned again soon enough), and with the P Bond nerf it can take Fire Blasts better and even go specially defensive to avoid the 2HKO if for some crazy reason Fire Blast becomes super popular. The point
Nelson Tangela brought up about Scrappy Kang being able to fight through Mega Sableye with PuP + Facade no long applies so now Sab is a guaranteed counter. Meanwhile, things like Gengar and Salamence remain nerf-free so I think it's finally time that Kang's usage will slip.