Supercharged111, I think the real confusion is in how people define/interpret the term "transmission flush". To many of us, a transmission flush is a process where a service facility connects a pressurized machine to the transmission system and it forces out the old fluid, sometimes sends through a "cleaning solution" and then puts in X number of quarts of new transmission fluid.
In my opinion, what you are referring to is more of a "clean version of the ole' spill and fill ATF fluid and filter change' maintenance procedure. I myself have used this procedure to pump 3 - 5 quarts of transmission fluid out of the transmission because the transmission pan did not have a drain plugs, and I was simply replacing however much AT fluid I got out with new AT fluid. Yes, your method gets more old fluid out at one time, but because I do not wait until 30,000 to 50,000 miles before I do my initial AT fluid spill and fill, I am primarily replenishing and fortifying the AT fluid's additive package.
I do this every 10,000 to 15,000 miles.to ensure my fluid does not get burned AND to ensure that I do not drastically change the chemistry of the transmission fluid. This way the varnish that has formed on the clutch material is not stripped away and it stays where it needs to be.
Now, I have never heard of a transmission in good shape failing your method or my method, I have heard of people who do have existing transmission problems who get a spill and fill transmission service performed, seeing a transmission failure shortly after the spill and fill maintenance. In all likelihood, their transmission would have failed without the maintenance.
Now, Ravalli Surfer was in the transmission repair business for a lot of years and has a great deal of valuable experience that he is generously willing to share with all who frequent the forum. Hence, he prefers to refer to maintenance or repair procedures by their industry standard names. Hence, when he "hears" someone refer to a transmission flush, he automatically thinks of the procedure involving the expensive, pressurized transmission flushing machine that many service providers use to fleece customers.
Now, with that kind of a transmission flush there is a very real chance that a transmission that has been poorly maintained over the miles and the years, and is subjected to a flushing procedure which literally shocks the automatic transmission system, will have a catastrophic failure within a very short period of time. He made a lot of money repairing/rebuilding transmissions that failed because a service provider was more interested in getting another $100 - $200 out of a customer.
So, I guess in closing I would say "...now you know the inside story..."
Regards!