That's only the case for CPU/MB/RAM, because the interfaces are tightly coupled (you want to upgrade your CPU, but the new one uses an AM5 socket so you need to upgrade the motherboard, which only works with DDR5 so you need to upgrade your RAM). For other parts, a "Ship of Theseus" approach is often worth it: you don't need to replace your 2TB NVMe M.2 storage just because you wanted a faster CPU, you can keep the same GPU since it's all PCIe, and the SATA DVD drive you've carried over since the early 2000s still works the same.
I expect many users would be happy with the above final state through 2030, when the AM6 socket releases. That would be 13 years of service for that original motherboard, memory, case and ancillary components. This is an extreme case, you have to time the initial purchase perfectly, but it is possible.
Your point kind of disproves your point.