Your paragraph has nothing to do with the story at the link.
I am an American currently living and working in Saltillo Mexico. I too have an FM3, however I did not have the difficulty getting the FM3 that the writer had. I simply needed a letter from my company, signed, notarized and apostilled plus a copy of my passport.
My FM3 is good only for one year at a time. I have had to renew it each year.
I often wonder if some of the anecdotal stories we see and hear are true or exaggerated to promote a particular point of view, and I think we have to be careful to not buy them too easily for it ends up damaging our own cause.
Having said that can you shed more light on your experience vs that in the story? Do you think the other story was made up? Does the experience vary from jurisdiction to jurisdiction. In other words, what is the truth regarding this matter?
The poster's paragraph is a direct copy & paste of the last paragraph of the "story at the link."