Something else to consider when taping up that bolt hole is that you just covered up a way for air to get into the machine. If air can't get it it can't get out which means it can't carry any dust with it.
I agree that might be the case on some saws depending on other gaps around them. In my case on the parkside I did test cuts with and without the opening covered. With the opening uncovered (and vacuum on) I could clearly see more dust being produced and some even escaping from that hole, covering it over made a massive improvement in my opinion.