20 years ago I was hopping from Intel to AMD and then back to Intel. After that practically every decent jump in CPU performance on the Intel side of things meant a new socket (LGA775, 1156, 1155, 1150, 1151...). AMD typically kept sockets for a bit longer but wasn't as competitive until Ryzen which had a few jumps in chipset compatibility in there.
In the last 20 or so years if I wanted a few years newer CPU for whatever reason it usually meant I needed a whole new motherboard, and that often (but not always) also meant new RAM.
In the last 20 or so years if I wanted a few years newer CPU for whatever reason it usually meant I needed a whole new motherboard, and that often (but not always) also meant new RAM.