I'm not splitting hairs. Your suggested title would simply be incorrect, whereas ours is perfectly fine.
Yes, it is worthy of criticism - after all, if you'd had recently put down $500 for a B450 motherboard with the hope that it would provide some future upgrades, you'd be right disappointed. On the other hand, if you'd gone with a $140 X570, you'd be pleased with your decision. Mixed backwards compatibility seems like it's asking for trouble: to me, it would have been better if AMD required a full new chipset for Zen 3.
Same socket, different chipset - personally I think AMD and Intel need to clean up their act with this kind of nonsense. It's a lot better than it has been in the past, but both could do with setting out their roadmaps of backwards compatibility (or not, whatever the case may be) with far greater clarity.
Like yourself, I tend to get a whole new setup when I upgrade my CPU but it's always frustrating having to tell people that request advice on updating their 5 year old PC that they just can't slap in a new $250 CPU.