Hell, we can even chase that one back further, remember how much money Bose spent in the '90s convincing people that tiny speakers plus magic can somehow sound comparable to a proper stereo or home theater system? They were absolutely full of shit, but a ton of people believed every word of it.
Then why is what comes out from my "modern" soundbar so crappy compared to the one I bought 15 years ago?
I had to retire my ancient soundbar because it had Bluetooth without security and would regularly pump out 100db of some show that our neighbors were watching at random times.
However, the sound quality was vastly better than any soundbar I can buy now--even my wife complained about the soundbars we tried--they were that obviously worse. I had to suck it up and buy a full blown sound system to match a stupid cheap-ass JBL soundbar from 15 years ago.
I remember buying that soundbar (back at Fry's!) and all the soundbars were pretty much just as good (well, the Bose ones were garbage and overpriced, but let's not get started about that ...). They weren't audiophile quality, but they were good enough that an amateur like my wife really couldn't tell much difference.
What the hell happened that caused soundbars to go to shit?
Soundbars today are a cheap addition to make up for the horrible sound on everyone's cheap $300 LCD 65 inch TV that in addition to horrible sound looks worse at 4k than the 720 Plasma did.
IIRC the idea is to have two crystals, one at a constant e.g. 100khz, and the other at (100+x)kHz for x corresponding to the sound you want. By physically connecting them, you get the sum (ultrasonic, lost energy but not a problem) and the difference - which is the sound you want - with most of the physics across half an octave so easily flat. Something along those lines.
Given a high enough sound pressure level, your own eardrums might end up providing the required nonlinearity. The warranty sure sucks, though.
objectively or compared to similar bluetooth, noise-cancelling headphone? Most of the reviews I heard agree that even a mid-tier IEM or wired headphone beats shit out of them.