I get you, I do, I just don't see why that should lead to Intel, who have a much worse track record and where you can be absolutely shure one socket will only support two CPU "generations", the quotation marks indicating that what Intel perceives as two different generations is not what you and I would perceive as such.
I had bad experiences with AMD, too, I bought one of the first AM2 Mainboards in hope of upgrading to Phenom later. Only it was an Abit KN9 Ultra and Abit went benacrupt a short time after Phenom release and only some of their last AM2 Boards with nForce 520 Chipset got Phenom support. Had I bought a Gigabyte or Asus with nForce 570 Ultra/SLI or one of the first P965 Boards, I would have been able to upgrade from my Athlon64 X2 3800+ to Phenom II X4 945 or Core 2 Quad Q9650, instead I was stuck with X2 5400+ BE@3,1GHz until I upgraded to my current Haswell board.
There I was sure I would upgrade my i5-4670K to Broadwell i7, only it wasn't to be since Broadwell needed Z97 and wasn't all that good. At least we got the 4790k, which I only bought two years ago.
Yes, the 400-series only happened because the 300-series boards were not designed all to well. Yes, it would have been better if 400-series boards could have used PCIe4.0. Yes, it wasn't nice that AMD didn't want to enable Zen3 on 300 series. But it happened, allthough late. But even that an upgrade to Zen2 was possible on nearly all boards early on is much more than ever to be exspected from Intel. Yes, TR40 and TRX40 was horrible for enthusiast buyers, but no one would have asked that of Intel. To be fair, HEDT seems to be dead for the time being, so there seems to simply have been no business case for non-pro Threadripper 5000 and we won't get a new HEDT plattform from AMD.
When I buy an AM5 mainboard, I can be very sure it will at least support three cpu generations. If i had bought a Z690 board early on it would have been ok to upgrade to Raptor lake, but I couldn't decide last year. Now I know Z790 won't get anything better, apart from overpriced 13900KS. I would be nuts to chose Z790 over AM5 if upgradeability is important to me.