Re: Betamax myth again...
Quality was why Betamax won in the professional market. You could find Beta machines in plenty of TV studios for that reason. Price was less of an issue there while generational preservation was.
As for stereo, I recall VHS had an easier time getting Hi-Fidelity sound onto the tape (especially in NTSC recordings) which is why they got an edge in sound and another reason VHS won that generation's video war. By the time Beta had a suitable answer, the war had pretty much run its course.