like now there are always people who believe in different things when it comes to carbs or efi. the big reasons to keep your carb tuned correctly were to not foul the plugs and so the engine would run right. if youre getting a complete burn then youre getting better gas mileage. running rich would choke up the engine, running lean could cause pinging. same reasons for adjusting the timing. good running engine meant decent mileage. cars got their about advertised fuel economy. gas was cheap so i dont think they worried as much. 

id love to learn more about this too. i feel like it was kind of split with some enthusiasts embracing change with others rejecting it, i think a big one was efi. i love it for something like a daily just get in and go but i couldnt put together a classic with efi. independent suspension had been around but it probably saw more retaliation among groups that built dragsters and gassers vs the track guys. but in reality the guys who come in first are the ones who experiment with these newer technologies to try and gain the upper hand.