"Necessary", no.
"Recommended", yes.
Your license likely either won't activate, or will eventually move to "unactivated" the next to you ping Microsoft's servers, if you just plug in your old drive. Link your MS activation/license to a MS account to help with migration.
Beyond that element, while the same chipset does make it a little smoother (vs say Z370 to X570), you can still run into all sorts of driver conflicts etc that are near impossible to diagnose. If you start with a clean installation, you know where you stand.