That's your interpretation of the regulations/law, Longford, not what has been happening in practice for many years.
I find it a bit silly for anyone to point-out that a participant or participants on this forum is/are expressing an opinion. Probably 99.9% of the comments expressed on this or any other similar forum are just that .... opinion. Opinions is why people participate in forums. Web forums typically advise participants not to rely on conversations on the forums for legal or medical advice.
If a question is crucially important to someone they should consult a qualified professional.
That having been said ... I respect your right to express your opinion, uninformed as I believe it is pertaining to the published regulations and/or law in this area.
To the best of my knowledge, there is no provision in the regulations or law which permits expats who establish residency in Mexico to do so on permission intended for and given to persons present in Mexico as tourists. If I've overlooked such a "tourists I'll appreciate your providing a link to it. Yes, there are INM employees who are either lazy, uncaring or corrupt who will allow an expat to do something contrary to the regulations. Ineptness and corruption is a hallmark of many government operations in the country.
Instead of encouraging people asking questions on the topic of Mexican residency requirements to circumvent the regulations/law (or guiding them relative to how its done), it might be best if such people asking the questions were first directed to the regulations so that they, themselves, can make a determination of what to do given their particular, personal circumstance (which, most of the time, are not fully known to us).
I think it's obvious that Mexico has been tightening the 'noose' on illegal aliens both by adoption of the 2012 revised regulations, by the increased vigilance at some entry points and also by the current amnesty - an amnesty (for lack of better description) which, as I've read the public statements (yes, another "opinion") may well exclude expats/foreign migrants who've said they're "tourists" (or who've been present in Mexico on non-existent or long-ago expired FMMs) but who actually residents in Mexico (some for a period of years).
But, to come full circle ... maybe instead of claiming, as if it's a surprise, that someone has expressed an opinion on this forum ... someone create a symbol identifying what someone says as absolute, irrefutable fact. However, who will be the determiner of "fact"?