Is the vent from the pcv valve back into the air intake really needed?

The PCV system reduces pollution by collecting "blow-by" (unburned gasoline and oil vapor) that would otherwise be vented into the air we breathe. The PCV system routes blow-by back to the intake system so it can be burned properly. PCV is designed to handle these by-products correctly; it is not harmful to the engine.

Placing a closed container on the end of the PCV hose will not work. The engine constantly generates blow-by as it runs. Closing off the end of the PCV hose will raise the pressure inside the engine until the PCV hose (or one of its connections) bursts, your collecting container ruptures, the engine oil dipstick pops out, or one of your oil seals leaks or blows out.

Moreover, leaving the open hole on the intake side will throw your fuel/air mixture off slightly if the hole is downstream of the air mass meter. At a minimum, you're letting unfiltered, dirty air into the engine, which will cause it to wear out faster.

What I see missing here is the fact that the PCV system does far more than just retain EPA compliance, the blow-by contains dozens of damaging compounds that must be removed as soon as they enter the crankcase by fresh air entering one bank, and the foul nasty vapors evacuated or "sucked" out the opposite bank while still in a gaseous state. If you do NOT constantly flush and evacuate these completely, then this water, sulfuric acid, un burnt fuel, abrasive soot and carbon particles are left to settle in the crankcase and cause sludge and greatly increased wear to the internal parts. The functions of a properly designed PCV system are many, and the emission portion is only one. Your engines would not last more than say 50-70 k miles like the old days (of course oil is far better formulated now) when these damaging compounds were left and only a draft tube was used.

I think everyone is missing the point of the catch can in the first place. The catch can sole purpose it to keep oil from going into your intake and being burn, which is BAD for the environment. You would put the catch can INLINE with the PVC return line to the Intake. When installed this way (the proper way), it is still recirculating the fumes, but lowering your emissions out of your exhaust due to you NOT burning oil anymore.

As far as what you do with the trapped oil, take it to AutoZone, O'reilly's, Pep Boys, Advanced Auto Parts... etc, they all accept used oil for proper disposal.

This simple method took my Gross Polluter, 230k+ mile, 1991 4Runner to passing smog out here in CA.

I think people are getting confused. There is something called a pcv/ccv which has a tiny hole and acts as a valve. Usually further away from the front of the vehicle.

Then, what I think OP is asking about, is basically a vent that goes into your air filter which is often misidentified as a pvc valve and ordered incorrectly because they look identical at a glance. It has a large hole and literally is just an elbow. They are not the same thing and If you accidentally swap them you will have problems.

It is returned through the intake because the vacuum presure of the intake matches the crank pressure that needs to be released. You could. Run a mechanical or an electric vacuum pump to release the crank pressure, they say a mechanical pump is better, run of a belt it pumps more at high rpms and less at lower rpms. The right amount of vacuum at the right time. So I have read!. Apparently too little or too much vacuum is bad for the engine. May be not bad maybe just not as good as it could run

If you use an oil catch can designed to catch the oil and fuel vented from the engine in line of the the PCS valve hose and vent the other end into the intake you are still 100 percent legal. It will also help the engine because you are not coating the intake side of the engine and valves with oil and fuel deposits that over time rob you of power. I would keep doing some research on this if I were you. For new direct injection turbo vehicles I would recommend doing this to all of them. https://www.roadandtrack.com/car-culture/buying-maintenance/a27182434/how-oil-catch-can-works/

Nobody got the point here. You are all talking about the environment. If you retain the pcv valve and connect a hose to the catch can, there wont be enough hole to trigger the pcv valve, it needs a vacuum, to pull the crankcase pressure. You want a "pcv delete". Drill the pcv valve, remove the spring and other valve mechanism inside so it will be just an air passage, completely hole, no valve, and connect hose to the catch can. Dont forget to plug the vacuum from the intake.