That's bullshit. It'd be stupid to invest in a new-old stock CPU, but the used market exist.
"A Stitch in time, saves 9", approach doesn't really work here. They won't save any money overall, after the next upgrade, if they move to Ryzen this upgrade - which is the entire basis in your claim, in saying a ivy/sandy upgrade is not worth it.
"A Green CX" 750W is more than fine. The new CX-M uses the same old platform that that used.
There's never been a VS750. Corsair for the most part, keeps wattage and quality somewhat together (unlike other brands).