AMEX put restrictions on Bonus offers to limit hopping between cards Language was just recently added for all Delta AMEX cards.

*50,000 Bonus Miles*
You can earn 50,000 bonus miles after you make $3,000 or more (the "Threshold Amount" in eligible purchases on your Delta SkyMiles® Platinum American Express Card...
https://www.flyertalk.com/foru....m/delta-air-lines-sk