Here's why the Cowboys will never do what the Rams do.
The Cowboys value their draft picks WAYYYY too much. The Rams take advantage of teams that value draft pics WAYYYY too much.
The Rams know that they can trade their 1st, 2nd, 3rd, or whatever pick for a proven Pro-Bowl level talent while the Cowboys hope they hit the lottery with their picks. The Rams use their draft picks to trade for players that have already proven to be good, while the Cowboys will use theirs to take a chance on Taco, LVE, Jaylon Smith, Trysten Hill, or Connor Williams.
When it comes to FA the Cowboys philosophy is once again completely different and loserish. They value their own talent WAYYYY too much and focus on resigning them each year. While the Rams will resign guys that have proven to be worth it and look for upgrade in FA for guys that are not cutting it.
If the Cowboys had drafted Jarred Goff and he lead us to a Super Bowl appearance as he did for the Rams he would be under one of the biggest contracts in NFL history right now. The Rams knew that he wasn't the guy and traded him away for a guy that is actually THAT guy. The Cowboys would have NEVER done that simply because Jerry would rather win with a guy he drafted so he can say he's right about something.