Actually, advances in technology are what have made decent 2-way systems practical. Small (7-inch) woofers have been developed that will respond OK up to the point where a tweeter takes over. Using two of these little woofers produces OK bass. In the bad old days, we used 12-inch (or 15-inch) woofers that were only good to about 1000 Hz, so a midrange driver was essential.
Even today, especially for high sound level, a specialized midrange driver is best. True, the design of a three-way passive crossover is a lot more complex than a two-way. You can't just put two two-way crossovers in series. But it can be done. One practical approach is to biamp the three-way so that only a two-way passive crossover is needed.
Even today, especially for high sound level, a specialized midrange driver is best. True, the design of a three-way passive crossover is a lot more complex than a two-way. You can't just put two two-way crossovers in series. But it can be done. One practical approach is to biamp the three-way so that only a two-way passive crossover is needed.