Megadeth and Slayer were on record labels that stood behind them. And they may have charted high, but they fell off the charts rather quickly. And Countdown and Youthanasia and Cryptic were a huge shift for Megadeth in terms of their sound after Rust In Peace, in fact, moreso than the shift in sound from POT to SOWN.
And why was Megadeth's and Slayer's record labels behind them? Because they still had fan support and they still sold. Why was Anthrax's not behind them? Because their fan base had eroded and they did not sell. Why did they not sell? I will give you a guess.
And there is no way that Megadeth's shift in sound anywhere near as drastic as Anthrax's. Megadeth got more mainstream but was still, basically, thrash metal. Anthrax sounded nearly grunge on SoWN. It was a major shift.
The biggest shift Megadeth made sound-wise was, coincidentally, their worst selling album; Risk. Or maybe it was not a coincidence? Metal fans show little tolerance for major shifts in sound. As evidenced by SoWN and, to a lesser extent, Risk.
Both made a calculated risk when they changed sound. They hoped that they would only lose a few die-hard fans but make it up by picking up mainstream fans. They did not, in either case. However, Megadeth attempted to rectify their mistake and go back to a heavier sound, Anthrax did not. And now you see where both are.
And, by the way, those albums did not fall off the charts quickly, not by metal standards at least. Metal albums in
any era tend to fall off the charts rather quickly because the die hard metal fans buy in the first week and metal albums dont tend to sell outside their fanbase often. Nonetheless, Metallica, Slayer and Megadeth were all successful in the early '90s, mid-'90s, late '90s and on. Anthrax was not after Persistence of Time. You can continue to try and deny that it was the change in style and John Bush that caused the downfall but it doesn't make it any less true.
The Bush era nearly killed Anthrax and, until recently, they were a shadow of what they once were as far as fan-base is concerned. It's not fair because there were some good songs in the Bush era and Bush is a great vocalist but thats the way it is. For most metal fans, Joey
is the voice of Anthrax. Period. Full stop. End of story.