Just ran into this yesterday on one of our webservers. It prevents FTPSVC from restarting properly as well. Had to resort to an unexpected reboot of the entire server to recover after FTPSVC hung which caused IIS in turn to hang as well.
If the SM Installer is doing a iisreset or net stop WAS /Y & net start W3SVC during the IIS configuration step of installation, you can bet your bottom dollar that KB4338815 would be to blame...although it sounds like it is also affecting many services during a start or stop, so the Installer would bomb out long before then when it first tries to start the MailService after installing all the files.
I'm going to be keeping my fingers crossed that I won't have to restart any services on any Windows servers until MS releases a fix (and if not fixed by next month's Patch Tuesday I'm just going to follow your example and remove it).