I recall this discussion. You are right when you are thinking from the point of view that the way the mask functions is to prevent the wearer from catching the virus from someone else or from fhe environment. Ie the mask actually filters and catches the virus on its surface. Then yes if you touch the dirty mask then touch your nose or mouth then the virus actually is transmitted into your body.
This was why at the beginnig we said masks probably dont work.
But along the way there was the thought that enougj people wore masks then those who were covid positive and wearing masks would have droplets from mouth and nose caught in the mask they are wearing nad hence make it harder for them to infect others. Ie you wear the mask to protect others from you if it turns out you are covid positive and didnt know.
That one has less to do with how the user wears and handles unless they touch mask them toucj surfaces which others also touch.
Again data might not tell the whole picture. Cos when presented data is often biased already and used to justify a prevailing idea or hypothesis.
The whole issue regarding the effectiveness of masks boils down to the mode of transmission of the virus.
If droplets are required to transmit sufficient viral load to cause an infection then masks should do a good job.
However if the primary mode of transmission is via aerosols then masks won't be effective because aerosols are like smoke and we have already seen numerous videos that show how masks do nothing to prevent smoke from spewing out in all directions.
It looks like aerosol transmission occurs on a regular basis because there have been numerous reports of those in quarantine transmitting the virus to a neighboring hotel room via the ventilation system.
The fact that indoor transmission has been shown to be the primary means of super spreading while outdoor transmission is rare further supports the evidence that aerosols play a significant part.
I'm sure masks would help if they are worn and disposed of the correct manner. However because most people just wear masks so they don't get fined it is pretty obvious they aren't going to bother with the technicalities. That is the reason why data from the ground shows that masks don't work.
We don't live in a perfect world so mandates need to be practical not theoretical. Human nature has to be taken into account.