A successful design is the BBC lS3/5a, a cabinet flexible and dead due to its construction (one example was discovered to sound better than it should, on investigation it was found that one of the glued joints was badly done, so apparently, they thought about deliberately badly gluing production units, until they thought better of it), it's also so short from the front baffle to the rear, that there isn't enough room for the sound wave from the back of the cone to bounce back, helped by the steep crossover slope. Due to its small size and lack of bass, internal pressure is unlikely to deflect the panels.
I think one problem is that the back-wave reflections, mechanical vibrations from the driver and the pressure deformation of the enclosure all act together to make a muddy sound, if you get rid of one it can make the others more obvious, ironically (possibly) making the speaker sound worse.
I think one problem is that the back-wave reflections, mechanical vibrations from the driver and the pressure deformation of the enclosure all act together to make a muddy sound, if you get rid of one it can make the others more obvious, ironically (possibly) making the speaker sound worse.