Don't take anything people say on youTube seriously, they're all idiots as far as I am concerned.
Genres do help categorise music, the metal scene must seem insane for names of genres and I'll admit that it is and I'll even admit that I have been confused before now, however, the names are quite descriptive if you think about it and can help when you're recommending a band:
"Well er, they're sort of a melodic death metal band, but at times symphonic or even operatic."
To me...I have an idea of how such a band would sound, because I like that sort of thing, I might go and listen to it. It's better than, "I'ts heavy metal", because it'd cover such a huge broad range of styles.
I don't tell people off if they get it wrong - I may correct them sometimes, just because they'd probably prefer to. My Mum's a metal-head and she doesn't have a bloody clue, she calls Kamelot gothic and well, I'll allow her. It's not as if it's all that important.
When it comes to the electric genres, I probably look just as foolish, my friend is DJ and it's all 'electro' to me, but it might tell me it's drum and bass or trance, but I'll admit it, I barely have a clue...saying that, I can spot D&B fairly easily.
