Because it means people think the regulations are for their (the people's) benefit, instead of being for the benefit of the capitalists, as they actually are.

Because there's a difference between the benefit to the whole society and the benefit to a particular person. If one person can set up things so that resources flow to him without him contributing any value in return, it's great for the person, but bad for the society. Some regulations work exactly in this way. It's great for certain people occupying profitable positions, and if it's less great for everybody else - well, sucks to be everybody else, tough luck.

"Capitalists" are just people living in the system, and some of them would seek such positions if available, and love it if they successfully occupy them. Those are the people that think it's ok to demand money from people singing "Happy Birthday to You". Why wouldn't they love it? Yes, it's not good to everybody else, but it's good for them.

Capitalists love it when people think that regulations are opposed to capitalism because then people will generally be against regulations, this allows capitalists to get away with things that make them greater profits like not disposing of waste properly or capturing markets with monopolistic practices