2020. I´d be on W11 now if it wasn´t for the missing UI option not to combine windows. Hard to understand why we renew our hardware, update drivers yet cling on to outdated OS for decades - smartphones are much more restrictive in this aspect.
Apart from when the old software doesn´t support or isn´t optimised for new hardware standards, e.g. USB 3.0 on Win7 (without 3rd party workarounds).