The Stanford study looked more closely at the masks than the MIT study which focused on social distancing (but likewise concluded no difference in transmission with or without masks). I think I have stated this before but there is no difference coming and going. The primary transport mechanism for the virus is through airborne particles. The size of the virus particles is roughly 1,000 times smaller than the opening size in even the N95 masks and probably much worse in the cloth ones. And that doesn't include the particles that escape through the sides of the mask, which are a substantial source of transport. So if you have the virus and are still breathing the virus particles will pass through the mask and escape from around the sides, rise up because they are warmer and move around a room. And if you happen to be wearing a mask and those particles get into your breathing zone they will pass through the mask and enter around the sides and you will inhale them.
The idea that you wear a mask to protect others makes no scientific sense. And wearing a mask to protect yourself from others likewise makes no scientific sense. What the masks do is reduce the amount of droplets should you cough or sneeze. However, those droplets have very little transport capability due to their size and covering your mouth will accomplish the same thing. And as recent guidance from the CDC indicates, there is very little potential for transmission on surfaces. Basically everything we have been told has been proven to be wrong.
The best thing people can do to reduce transmission is to stay home if you are feeling any symptoms. And no, asymptomatic carriers have never been demonstrated in any study to be a significant source of transmission.