Picture tubes started round, and then became rectangular: https://www.earlytelevision.org/prewar_crts.html https://www.earlytelevision.org/prewar_crts.html Th

Picture tubes started round, and then became rectangular: https://www.earlytelevision.org/prewar_crts.html https://www.earlytelevision.org/prewar_crts.html They didn't really have the problem of picking an aspect ratio because motion pictures existed and that was already 4:3