Instead of asking, "what was wrong back then?" we could ask "what's wrong now? why are people so obsessed with their pectorals?"
Most guys hate leg days. The effort is extreme, chest day is the easy day.
Leg days are no “extreme effort” to dancers, cyclists, runners, gymnasts, etc
It was my understanding that the reason most guys avoid leg day is because they're not "show" muscles. It's rare that you're not wearing pants so most guys who lift purely to increase odds of finding a mate focus on the muscles women do see.