It's worth noting the big downside to enabling PLPMD is of course that connections which are broken are unlikely to get fixed, but it can result in extra latenc

It's worth noting the big downside to enabling PLPMD is of course that connections which are broken are unlikely to get fixed, but it can result in extra latency or lower initial connection performance which is then hard to diagnose. As opposed to being just broken and fixed by the administrator/network operator/user/etc in the first place. Most of the time the MTU issues are relatively local to the user, e.g. their router isn't configured with the actual MTU of their internet connection, etc. and can be fixed by them (as opposed to by the ISP etc)