The problem with your solo guitarist virtuoso type of guys is that, although they can shred, they have no true songwriting substance like their "less technical", successful brethren.
Also, bands like Metallica, Slayer, Anthrax, Pantera, and even modern spin offs like Rammstein, constitute thrash metal.
GNR, Alice in Chains, Dream Theater, Zeppelin, solo guys, are different genres.