"I don’t know, nor do I care. I would rather the machine look brand new, and with my motor work, sound and feel brand new, than care about filtration."
It's not about looks. You should care about the filtration because that is the entire reason how a vacuum works. It has to be able to exhaust the air properly otherwise you will overheat, overload, and burn up the motor windings as well as the vacuum not being able to pick anything up to begin with. The old vacuums used the bag as part of the filtration system as well as the air path. Commercial vacs still do. If you never wash them and leave them to get clogged up, or they get clogged up in other ways, they lose their ability to expel and exhaust air, and what you have is the "blowing into a bottle" effect. Air is going in, but none can escape. This is still true today with bagless vacuums, if the filters get clogged and the motor cannot breathe, you notice the power cord will start heating up and growing warm as the vacuum draws more and mower power to try and run. Eventually the motor will burn up, that's why so many of them that were abused and not cared for sound terrible.