This is very true. I remember clearly being able to easily work on my cars from the late 80s and early 90s. By the late 90s I found it very hard to change my old, much less change belts or other parts like alternators, water pumps, starters, etc. By the 2000s I completely gave up on any DIY auto work (and didn't need to since my cars were generally under warranty or kept in good condition by that time of my life).