Just as an example of what I see so frequently... after finangling with different trip durations (13, 14, 15, 16 days to try to get every mix of offpeak travel possible with minimum stay requirements met) I was able to find... one flight at 280K SkyMiles in April for ATL to FCO (note that it is no better in September). I picked April and September strategically since they are shoulder seasons and should have the most capacity. Obviously anything earlier than March means that the 86K fares don't exist since they have a 90 day minimum purchase requirement. This 280K is with a long layover in JFK (want a short layover? That's an extra 30K SkyPesos). Want a nonstop? That's 450K+ SkyPesos.
I can go on Google Flights and find - with wide open availability - nonstop outbounds and one-stop return flights for $2.6K. I can get a superior flight (no connection on the outbound) with wide open flexibility for $2.6K whereas a crappy route with a long layover is 280K SkyPesos. If I want comparable routes that cost shoots up to a minimum of 350K and usually more like 450K+. That means that a .76 cent per mile redemption rate. And this is not specific to ATL-FCO - this is ATL to pretty much anywhere. CDG? AMS? It's all the same - <1 CPM redemption rates.
Delta's D1 SkyMile pricing is just punitive. Full stop. It's the most embarrassing thing about their program. No other airline consistently has so many routes at <1 CPM for J redemptions.