The thing with Glam was that they started softening rock again, specially when all where doing Power Ballads.Never forget, that once Danzig/the misfits chased Motley Crüe out of the Whiskey. Just as Alex chased this glam rocker out of the Iron Maiden temple.
I won't bring a subjective opinion about glam rock vs true metal (no true Scotsman, anyone?). But history is history.