Funny how it is a self created problem...LOL. He seems to think it was "increase in demand" for their premium products. Right!
No, it was the rollover MQM's & credit card deals that added so many to the ranks - some of them who aren't even "frequent flyers."
To stop overcrowding, cut down on the credit card passes! That seems like a no brainer. But it doesn't fit their revenue model.
That in addition to a modest increase in spend limits. Maybe $25k for DM? And how about the thinning that already is happening with the 2023 increase to $20k? That has to thin the ranks in some fashion, and has not been mentioned!

But seriously, you have to look at what value a DM will get at $35k spend:
Domestic upgrades: Sure, frequency maybe will increase with fewer DMs. But that is not a huge value in my opinion. Many people that spend 35k will just buy FC. It is tough to get 35k spend without purchasing FC. Those that do are serious road warriors buying tons of economy fares - not exactly the customer Delta seems to be targeting for their DM level. The big credit card spenders are also ones that probably just buy their upgrades.

GUC's: For me, (and I would image many others) the biggest value of Choice Beni's used to be the GUC's. You could get an $800 international ticket, and use a GUC for business class UG. That was a decent savings and value. And I will tell you, sitting up front on a 12 hour flight for $800 makes you feel pretty good!
But with GUC's decreased to one class upgrades, they lose their value. Why would I spend 35k, only to have the privilege of using my GUC to purchase a Premium Select ticket at $2500. I can usually find a business class ticket on another airline for near that amount. Very little value there.

Mileage tickets: Another value blast from the past! Using your vast bank of earned miles to get free tickets. After a hard year of travel and big $ spend, I used to be able to get the whole family of 5 some tickets to Europe or Asia. Now that is virtually impossible due to availability and sky rocketing mileage costs. Pre-Covid, a bargain hunter could find a business class ticket for 80k miles sometimes. Now those same tickets are ridiculously priced at 300k miles or above. A huge devaluation.

I spend around $25k on travel annually, and could probably make the $35k level if I really tried, using a combo of methods. I own my own business, travel maybe 8-10 domestic trips (usually buying FC) each year, and 10 international. It is the international travel I am mainly concerned with - thus the importance of GUC's.
I really fail to see what value I will receive for awarding $35k to Delta that I wouldn't get if I just spent that same amount by strategically purchasing domestic FC and international J from the free market. Maybe I am just not their target customer any longer. Too bad. I did feel some loyalty after 25 years and 2.6 million miles...