Once again, swapping CPU is very easy task. Swapping motherboard is like building whole new system.
Also your suggested upgrade is still slower on games and runs much hotter. Energy prices are rising btw.
Edit: You can get 12700K+B660 at same price as 58003D Only if using Amazon's discount. That can go away anytime. Generalizing that single store's probably timed discount applies to every country, every shop all the time is wrong.
It does not perform as well. You can easxily say that just looking at clock speeds and in real world
https://static.techspot.com/articles-info/2352/bench/Average-p.webp
No, 12900K is faster than 12700K. There is no conspiracy this time.