Vincit qui se vincit.
That's the culprit. A person who is truly into music doesn't care if it's classical, rock, pop, metal, etc. as long as it has a certain value. Melodical, harmonical, tonewise instrumental/vocal, rythm, etc. Nowadays Metal just needs to be gritty and sometimes technically hard to master. Pheriphery for example are incredible when it comes to technicality, but they are not bringing anything that grabs my ears attention.Metal fans, like many other music genres fans, have a tendency to become very conservative and narrow the possibilities of artists and start saying this or that band is not true metal.
That said I was never a fan of modern metal, even of the Nu Metal Movement years ago. Maybe I am a conservative in this regard too, who knows, but there're still great bands around like Evergrey who are delivering original but great music.
Maybe we are just spoiled by the great songwriting and talent from all the old groups that somehow can't be recreated nowadays.