First of all remember the terminology of the item. A folder is just that, a coin holding folder. An album is usually considered an item where the pages open similar to a wedding album, both sides of the coins are visable and they are enclosed with plastic slides.
There is nothing really wrong with folders except a few minor things. For one the glue as noted on the rear of the slots. Some coins are well worn and they tend to fall out of the slots so people wet the glue and the coins now stay in place. Some of those slots are tight so people have a tendency to push them into the slots with their thumbs or even a small rubber or plastic hammer. I've heard of people also using a brass hammer to push the coins into those slots. If you were to take a cut away view of the slots you would see the part that touches the rear is larger than the part farthest away from the rear making it necessary to force a coin into place.
If these folders are kept in a damp invironment, the glue will slowly absorb some of the moisture.
Any and all of the above is not the best for a coin.
Albums are OK regardless of the brand depending on how they are stored also. I've got well over 100 Whitman Classic Albums and each is encased in a Zip Lock Plastic Bag. I've got no problems with coins for well over 60 years now.
If for some reason any of my coins are effected by this method of storing in the next few hundred years I'll let you know.