I do think that played a part in it, but I also think design does too. Between the outter frame and the swing arm there is an adjuster it is hollow and on the end there is a hole that the bolt goes thru. between the frame and swing arm bushing technically theres nothing there to support the bolt. This was an issue years ago and it was causing pivot bolts to snap, then big dog did a recall on them and put hardened ones in, that were stronger, but there being no support is still an issue.
problem is that threaded adjuster on the right upright which is used to shim the swingarm. the ID of the adjuster isnt close to the OD of the bolt. giving it room to flex and break.
View attachment 75802
See the gap in the male part of the adjuster where the bolt goes thru, it isn't a snug fit and allows bolt to flex, same for the female part of the adjuster the hole is bigger than the bolt.
View attachment 75803
This is used to shim the rear swing arm also so there is a lot of stress on it and then you have the stress on the bolt from this and the flex every time your belt is pulling on the rear pulley.