The updates are often fatal, though. These include things like the Opteron "Barcelona" TLB bug and the first-generation EPYC "Naples" frequency scaling bug. The fix for the former knocked 20% off the performance of that generation of parts, and the fix for the latter meant that you had to run at the base clock frequency at all times, getting neither turbo boosts nor power savings. If you apply all of the speculative execution workarounds to an older Intel part like Xeon E5 v3 you will lose something like a quarter of the performance you paid for originally.