Dylstew

Okay, so I've been thinking about it.

Thrashcore is pretty much sped up hardcore punk. Powerviolence grew out of that. Powerviolence is pretty much what you get if you put the 80's hardcore punk to the biggest extreme. But it was still purely punk. It's only later some bands started incorporating metal elements to it. Powerviolence is DEFINITELY punk.

Crust Punk took Anarcho Punk, Hardcore Punk and some Extreme Metal.
However, Crust Punk itself is mostly like hardcore punk. Although it takes these Metal Elements, they're pretty light. They're kind of there to actually make a more extreme form of hardcore punk. The songs are simple and written similarly to punk songs, the songs are generally short just like punk, the vocals feel more punk than metal, etc.
Punk usually just had shouting/yelling instead of actual screaming/growling, but in Crust we do get these latter techniques, and they do have their own punk sound to them.
Crust Punk is again, DEFINITELY Punk.

Grindcore mixes Thrash, Industrial, Noise and extreme forms of Hardcore Punk (like Crust Punk). Many grew out of Crust and death metal. What it pretty much feels like to me is that all these other elements, again, are pretty much just there to make punk as extreme as possible. You get the short songs of punk, made even shorter. You still get the simplicity with a lot of anger and aggression, but a bit less simple because of the Metal elements. The Metal elements also make it more extreme. The screaming/growling vocals tend to be more punk, with a lot of energy. But later, it all depends on the band. Some of them tend to focus more on Metal, others on Punk.
Grindcore is a bit of both punk and metal. But it generally tends to lean more towards punk.
It's kinda like how Heavy Metal was there to be a more extreme form of hard rock, but then different subgenres tried making it more and more extreme. Grindcore is like Punk's Death Metal.

edit: Ofcourse Deathgrind leans more towards Metal.

Then we have Hardcore. The Beatdown Hardcore bands such as Madball, Sick of it all, Hatebreed and Terror had a bit of a different sound but still sound very punk. Later Agnostic Front also has a similar sound, despite starting as a thrashcore (pretty much sped up hardcore punk) band. It had a lot of parts that were more slowed down, kind of like what black flag later did with their sound. But you could still hear it was hardcore punk. You could see it as two branches of hardcore punk developing/evolving, going in seperate directions. The traditional hardcore punk bands and the bands that came after, and these beatdown hardcore bands and those that came after. Both progressing naturally. And the modern one again, wants to make a more extreme version of itself.

Eventually these bands caused Metalcore (Integrity, Earth Crisis)
I think this is why recent regular Hardcore tends to have Metal elements to it.
While Crossover Thrash mixes that traditional hardcore with Thrash Metal (which has it's roots in Hardcore Punk but is a Metal genre), Metalcore mixes that new form of hardcore punk with extreme metal.
I realize a lot of genres have their prototypes, such as the thrash metal bands that caused Black Metal. BUT I think with Hardcore Is just a genre progressing over decades, getting different sounds like most others do. I don't think it just has it's roots in hardcore punk, I think it IS a form of hardcore punk.


Traditional hardcore progressed from something like this:

To something like this (both straight edge bands):

It's a bit different but not too different. Ofcourse there's ones that pretty much copy the 80's style as well.


The modern hardcore progressed from something like this:


to something like this:


Why is this one so different? It's just the genre wanting to become more extreme and extreme, and the metal elements helped achieving that, but in the end you still get something that appeals more to the hardcore punk fans than metal fans You still can hear where it comes from, but while it did become it's own thing like you said, it fits punk to me.

The later modern hardcore bands being punk? I get it, it's debatable. But I think it fits the big spectrum. I don't think we need to make it a big rock sub genre separate from Punk and Metal. If we did that we'd get Rock, Metal and Hardcore, but it's not big enough for that.
I can still hear the hardcore/metalcore in this modern metalcore band, which again, is something different from the early ones: