I think you're both right in a way.

I think the takeaway from the original post is that you need the "right" gear, though not necessarily expensive gear. I empathize with his "why doesn't my Line 6 sound good" annoyance. There is an abundance of those questions. But throwing money at it isn't the only solution. There is a threshold--you're never going to get the digital distortion to sound like an over driven tube and that Crate cab is probably going to sound like shit, no matter what head you've got (sweeping generalization). But that doesn't mean to you need 4 grand for a Diezel.

In my estimation, $1000 is the buy-in for acceptable metal tone (to my ears). At that price you can likely find a JCM 8/900 2x12 combo on Craig's List or some other respectable classic amp. Throw an overdrive pedal in front and you're good to go. Short of that, you could get lucky and find a well-loved V4 for around $500 and pair that with a 1960a/b cab.

You can gain stage all you want, but unless you're playing treble-y black metal or 80s shred, you won't be melting many faces with cheap gear.