It has worked this way since the days of the vacuum tube, so there probably is some legal precedence somewhere. I think part of this with the NE5532 is just that these days most EEs spend most of their time with digital where the data sheet and its spec is absolute; in the linear world the spec sheet is an ideal and an average because the parts themselves are an ideal and the real world never lines up with the math. Back when the NE5532 came out it was still common to see power supplies that were unregulated or barely regulated or cheap regulators with poor tolerance that would vary a fair amount with wall voltage and massive tolerances on passives, data sheets and EEs took this into account, most parts would survive max voltage but there would be a higher failure rate, so run at 70% or 80% and you don't have to worry about it.

In these days of cheap SMPS and EEs that are trained with a strong lean towards digital and much improved IC fab, the max seems to be treated as the max safe voltage for good reliability and life, and you don't have to worry much about the tolerances of everything else so much. Back in the 90s when I was learning this stuff, the old EEs scolded me when ever I ran at max voltage and would patiently explain it all to me and that even if it can operate at that voltage, you can't be certain your PS will still be putting out that voltage in a year, parts drift as they age and accidents happen and the world is not ideal. They were right.