PeeChee Folders

Any of you older folks remember the PeeChee folder? I'd forgotten all about them until this morning when I noticed a post on my Facebook page with a picture of one.

They were ubiquitous back in my school days. Wikipedia says they're still available but the illustrations on the cover have changed. I don't think I've even seen a picture of one for decades, until now. The one in the picture is exactly like the ones I used.

Why were these so popular? They were just a damned folder but everyone seemed to have one.