Yeah, I'm not 100% on board with that definition of trolling either.
Certainly it seems to have come to be the term for being brutishly cruel or insensitive or inappropriate online. But the roots are much deeper. the term comes from trolling as in fishing, trolling a line to get people to bte. The joy comes when people do, and you string em along. Certainly the most boorish and witless is to be blatantly offensive or smugly throw passive aggressive insults intending to incite a reaction. often in those cases the "troll" is getting off on making others, specifically others that they view as opponents or adversarial, uncomfortable. This would be like someone prochoice yelling kill babies on a anti abortion site, and laughing as they get fumed up in some sort of masturbatorial self-gratification while they sit back and say "look see, I was right and clearly these folks are the crazies cuz look how worked up they got hahaha" and that's a thing, and it's trolling, but it's not good trolling.
It can be many things and isn't always so malevolent. I see it more like the digital equivalent of silly pranks- hooking up a hidden spare horn to your friend's headlight wires and laughing while they try to figure out what's buzzing. or swapping the keyboard with the computer next to you at the library and typing silly nonsense when the person sitting there tries to type. It's about laughing at the reactions you craft, and enjoying pulling one over with those others in on it. a digital practical joker or prank artist. it doesn't need to be abuse by manipulation.