Kathy_9 The fact this article even exists tells me that you are not the first or only one to experience
Wow talk about some very incorrect information, the author doesn't even realize all modern brake systems have dual master cylinders.
When the pedal goes to the floor, it’s usually caused by a bad master cylinder, leaking brakes, bad brake shoes (if "equipped with rear drums), and a few other reasons."
Leaking brakes seriously, it takes more than a single leak to put the pedal to the floor.
"bad brake shoes (if equipped with rear drums),"
What about the lining of a glued pad versus riveted letting loose?
"If any part of this system goes bad, the brake pedal can go to the floor."
The author is back in the 60's again.
"always put the lid on the master cylinder, you don’t want more air entering the system)."
Really then why does the Master Cylinder Reservoir not collapse as the pads wear down? Clue the lid has a air breather in it to let air in.
Maybe the author needs to go back to writing on simpler subjects as the brake advice is outdated and quite incorrect.