All speaker designs are a compromise. Think about the scale of musical instruments, from human focal cords an inch or so long to grand pianos. Now think about reproducing all of those sounds using a tweeter, a mid, and a woofer. Ain’t no speaker going to be perfect. By the early seventies, amplifiers were good enough that THD and IMD were below the levels that humans could hear and frequency response was flat within fractions of a dB. Speakers became, and still are, the limitation on getting a sound you like. Speaker design is part science and part art picking the compromises you make. Speaking strictly on numbers of speakers made, most are cheaply made and of poor quality, then as well as now. The difference is that the good speakers from the past were preserved while the poor performers were discarded. Now when we look at the handful of vintage models that survived, some people say vintage speakers were better than modern speakers. The real story is some vintage speakers were better than most modern speakers and some modern speakers are better than most vintage speakers. I run new drivers in vintage cabinets so I get the best of both worlds.