I don't know the term 'new HIFI sound' but if I was to explain it.
My interpretation is detail without coloration.
I'm in my 50s and the stereo's I heard in my younger years was enjoyable. And when I listen to older equipment (for the heck of it I pulled out an Adcom amp and replaced my Moon amp with it) the sound is less dynamic and detailed.
Ultimately, I think the reason there's some many options is because we all have different tastes. I hope technology has added the ability to pursue different characteristics.
Ultimately music appreciation lies in the beholder - if someone likes it they like it. And if they like it over Apple earpods or Boulder Audio with Wilson speakers does it really matter?