Might be the dumbest ? yet

Why is wall insulation usually "faced" while attic is not?

Can faced be put in the attic?

I'm guessing blown is cheaper and easier to install?

Actually the use of paper or some sort of aluminized foil is not recommended anymore...

The paper face is a potential media for mold etc.

The original thought was that this was the facing of the thermal envelope but actually the edge of the thermal envelope is (depending on who you believe) either the outside face of the sheathing or the vapor barrier (Tyvek) exterior to that.

You can now buy wall insulation that is cut slightly wider to allow it to support itself within the stud cavity.

Yes faced can be put in attic ceilings. Paper or facing towards you.

Johns Mannville

Facing is mostly for a vapor barrier and side benefit is for ease of application.
Depending on your climate and how your house is built you may or may not want backed(faced) insulation.
Down here in Texas the un-faced variety generally serves us the best.

Wall insulation a lot of times was faced simply so you could staple it to the studs to stay in place (aside from the vapor barrier aspect). In a ceiling/attic you're relying on gravity to keep it in place.

Some homes are built without the traditional insulation on the walls. Instead, holes are drilled into the block and it's filled with foam to act as the insulation.