The PCV gasses don't actually go through the injectors.
They go on them and around them. They leave a black gunk/soup in the intake manifold after a while, and deposits on the intake valves, the outsides of the injectors, throttle body bore and plate, and the ports where the intake charge flows. Then, it enters the combustion chamber to get 're burned'. Since it is not fuel, it doesn't burn completely or very well. More deposits are then formed inside.
This is why I use a PCV catch can.
BTW, older cars with carburetros washed the PCV stuff out of the manifold and valves to a great degree. Things are actually worse with fuel injection, deposit wise.