Punk's original ethos was "I don't like my parents' music and culture and I don't know how to play an instrument but I still wanna express myself". Tons of crap falls into that category, music that doesn't even classify itself as punk.
I find it almost impossible to classify bands as a single specific genre. They're almost always in a spectrum of multiple genres. You can try to say "X band is more punk than Y band", or "X band is more Y genre than Z genre", but to say "Agnostic Front is punk" would be problematic; Is it hardcore punk? Is it just plain hardcore? Crossover thrash? Who cares? It is more punk than Adelle, though.
I find it almost impossible to classify bands as a single specific genre. They're almost always in a spectrum of multiple genres. You can try to say "X band is more punk than Y band", or "X band is more Y genre than Z genre", but to say "Agnostic Front is punk" would be problematic; Is it hardcore punk? Is it just plain hardcore? Crossover thrash? Who cares? It is more punk than Adelle, though.