Sampling is not just cutting a fragment from a song and calling it a day. Usually (if you look at Prodigy's tracks for example) it includes transformation so that the result doesn't sound much like the original. For example, you can sample a single note and make a melody from it. Or turn a soft violin note into a monster's roar.

As for DJ'ing I would say it is pretty limited form of art and it requires lot of skill to create something new this way.

Yes, that's what people are doing with AI music as well. Acting like there's some obvious "line" of what constitutes meaningful transformation is silly.

I see DJing as more akin to being a skillful curator than being an artist. They are related but not equivalent.

I was a trance and dnb DJ, I definitely never claimed I was writing the songs I played and I think it would have been dishonest to do so.