When Black Sabbath started, Tony Iommi had custom equipment to get his distinctive tone. Bands that used the legendary Marshall JCM 800 often had it custom hot rodded to get huge crunch. Metallica did waaay back in the day. The point is that it wasn't easy to get the tone that the heaviest bands had.
Today you can go to any Guitar Center and buy a Mesa Boogie triple rectifier and get as crunchy a tone as you want. It is accessable, and therefore mainstream.
Here is Madonna playing the Pantera classic A New Level. Anyone can buy a Gibson Les Paul and a Mesa Boogie amp and get the classic sound. So in some ways the sonic mystique that hard rock and heavy metal bands used to set themselves apart is done. It's over. Sorry.
If everything is heavy, then nothing is heavy. If everything is brutal then nothing is brutal. And that sound that once had a specific meaning is now used to sell insurance and promote NASCAR. If bands want to set themselves apart, they will have to do it through their composition instead of their tone.