I have a return ticket that departs long after my initial Thailand stay (because I will come and go over to other countries, returning to Thailand in the spring) so the argument could be made that I don't have flight bookings yet to make certain that I am leaving Thailand within the terms of the 1 month visa I will get. But as with many things, this is up to the discretion of the Immigration officer in BKK (and also airline staff at every check-in along the way). In fact having paper-work permitting one to enter any country is never 100% certain. It is the first step, we can still be denied entry. The final gatekeeper is when we present ourselves with our papers to Thai Immigration when we land.
Would not surprise me if you you say occurs, but there are numerous problems with this, including the ethical one that those who succeeded getting their TP code after 2-6+ applications will get away with it, but newcomers will be punished.
I did the same and this trick didn't work for me. Now, I was snapping a photo of a printed paper of the QR code instead of a screenshot of the QR code. But I am sure if this was crucial Thai Immigration would have told us this.