When you look at it that way, it is pretty bad then, but with AMD you get a better CPU so maybe there isn't the incentive for them to bother.There were Intel motherboards as low as £150 which supported it. A basic Intel mini-ITX motherboard(DDR5 and equivalent of the A620) is available from around £100.
Just like AMD forced Intel to go above six cores,, maybe if Intel had a competitive CPU range the board partners would be forced to innovate again. I do agree with you in part, X870 is hardly a decent upgrade when you look at X670, very lacklustre step forward for what I'm sure will be a lot of money.