A bit harsh... but I see your point. I hope you realise that the people you're referring to are also looked down upon among the DJ community - they play pre-recorded sets, mime random knob-turns, etc.

Some of them genuinely love their music and are great to hire to really liven up an event... a playlist can't read a room, but someone at the decks can cue up a track that they know will follow really well from the previous one, and introduce it accordingly without any disruption in the beat. Weddings, clubs, parties etc all benefit from a DJ.

I probably wouldn't go a festival just to see a DJ though... that's when you end up with the sorts that you've identified in your post.