Intake manifold blockade?

What matters is getting the cover off the bottom of the intake. That MUST come off and be cleaned.

Ive seen more junked engines because that wasn‘t removed and cleaned I can’t count them all.

Not taking that plate of is a HUGE mistake.

Can you elaborate on why this will junk an engine?
I tend to clean anything/everything just on principle if I have it apart, but I'm curious about what is so devastating up under there. Old high mileage motors have lots of baked-on sludged-up stuff in them, no?
Obviously, if one was going to sandblast the intake, you'd want to get the media out from under, etc.