For simple and slow communication busses on hobbyist boards, sure it probably doesn't matter.

But I really can't trust this very superficial attempt to prove a negative with regards to a very complex phenomenon that I do not think he understands, especially since he mentions nothing about inductance, reflections, or impedance changes.

Hell, RF experts with decades of experience will still find new corner-cases and issues with PCB layouts when it comes to analog signals.

In terms of "actual wisdom" regarding 90 degree traces: Some time ago at my job we had to actually scrap a PCB because of right-angle traces causing too much interference. The end effect was a comb filter on the signal and a ton of emitted RF interference.

TLDR: Yes, the phenomenon is real. Do not trust these hand-wavy attempts to dismiss it.