I don't think this is true at all.
The Cards were going to assume about $235M of Stanton's contract and send a pretty underwhelming group of prospects. Assuming the $60M the Marlins were going to eat would be due only if Stanton opted in (consistent with the $30M paid to the Yankees), Stanton's contract would have broken down as:
2018: $25M
2019: $26M
2020: $26M (opt out/in)
2021-2027: ~$20M
If the Braves young pitchers had not completely crapped the bed in 2016 and 2017, the Braves would be in position to potentially add that kind of contract with a $130M payroll in 2018 that should be rising.
Stanton almost certainly wouldn't have agreed to a trade to the Braves, but to say there was no way the Braves would never have been in on him is completely wrong.
I've always worked off the premise of
can it be done when it comes to Stanton, not should it be done.
It appeared to me back in mid-season when (at least for me) there was a likelihood of a payroll increase from 2017-2018 and that the Braves would be looking to make a
splash move to energize the masses for the new park. Trading for a Mike Archer doesn't do that because how many of your casual fans know who Archer is? Same for signing MM. But, if you trade for the guy who's on Sports Center hitting 500 foot HR every night that's different.
I think Stanton could have been an option until, like you said, the young pitchers crapped the bed in 16 and 17 but ALSO when it became clear to ownership that they had a group of bumbling idiots running the show which IMO was well in advance of HartCoppy Gate, probably about the All Star Break.
Let's spin reality a minute and say that Teheran stayed a solid 2-3, Folty developed into a reliable 2 with at least some hope of moving to a 1, Blair and Wisler at least showed that they were good back end starters and one of Gohara, Sims or Fried had burst on the scene looking good. The offense is similar to what it currently is with Freeman (LH power hitter) and Inciarte and Albies at 1,2. Then from the Braves stand point you can see how Stanton makes sense.
Also, given the better tax situation of living in Atlanta vs NYC and the fact that Atlanta is selling Stanton on the idea that they are entering their window, I think it really possible that instead of 4 teams there would have been 5.
Remember, I'm not saying it was the right move. I'm saying it looked like a move that they were setting up to do.
But the Braves killed any hope of that (and maybe for the best) through their own ineptitude.