It's both a mix of some players being bad and some players simpley not being experienced.
There's a A LOT of people in EVERY fighting game that will dub something OP if it makes them have to act in any way different from how they want.
Well I'm sorry people but when it starts to rain and you have an umbrella in your hand then you claim the rain is OP because you'd have to use the umbrella to stay dry then there's something you need to consider trying before claiming such things.
Sackboy defintely needs a nerf! I would rather have his Lv 3 nerfed instead of his AP. Most Sackboys would just camp at the edge of the screen, and the idiots im playing FFA with would just walk into his cake. I would literally be the only person grappling him! His lv 1 is useless and not many people go for it. His lv 2 is okay, but his lv 3 is the strongest! Even after death they still leave you as a bubble. Thats like Dante's lv 3 leaving you frozen after death for example.