I don't believe they're weight police....you find those at the scales.
I believe they're just owners trying to help educate an unsuspecting/uneducated owner as to how it all works in the real world vs. what the salesman say. I was that unsuspecting/uneducated guy at one time and so I'm appreciative that they all laid it out for me.
For instance.....I had loaded in to my 5th wheel about twice the weight that I suspected I had loaded....and I thought I was guessing extra heavy at that. I also never considered the weight of the 5th wheel hitch itself, the weight on my in bed tool box and all that I had in there....being added weight to the rear axel. Hell, I thought I was doing myself a favor by taking some of the small heavy stuff from the trailer and putting it in my tool box. Once I was educated to all the numbers it became so "obvious".....but if you don't know...then you just don't know.
Of course I could be all wrong....this is all just my humble opinion. These guys could really be weight police. LOL