I can confirm this; cachers back then, even more experienced ones, just didn't have a sense of what would survive in the elements. My very first find, in 2002, was a yogurt container taped to a tree. It was a few weeks old and the lid was already cracked. Plastic bags for logbooks were rare, even in inherently leaky containers like Altoid tins. Cheap generic tupperware and repurposed food containers of all kinds were prevalent. Once I found a cache made from plastic VHS tape box that was too warped to close. "Another lame micro in the woods" was a meme by 2005 at the latest. Swag was more common, yes, and 95% of the time it was stuff like McDonald's toys, business cards, pennies, and assorted dollar store crap.
The quality issues today are different. They aren't notably worse.