Mozartfan,
Most of the speakers up to the early 1960's were high efficiency speakers. In those days the speaker were quite large in size. But, when stereo came along and television sets were also populating living rooms, it became important that speakers become much smaller in size. The "air suspension" (sealed box) speaker came along to solve that problem. These speakers were inefficient, but, solid state electronics came along that offered higher power in practical packaging.
There has been a small revival in higher efficiency speakers and lower-powered amps, but, it remains a boutique community because the rest of the world places higher priority on small size (you can just plop the speaker on any table), portability, etc. and sound quality hardly matters that much.
Most of the speakers up to the early 1960's were high efficiency speakers. In those days the speaker were quite large in size. But, when stereo came along and television sets were also populating living rooms, it became important that speakers become much smaller in size. The "air suspension" (sealed box) speaker came along to solve that problem. These speakers were inefficient, but, solid state electronics came along that offered higher power in practical packaging.
There has been a small revival in higher efficiency speakers and lower-powered amps, but, it remains a boutique community because the rest of the world places higher priority on small size (you can just plop the speaker on any table), portability, etc. and sound quality hardly matters that much.