rpcbind.service is currently pulled in by multi-user.target unconditionally, even though it is socket-activated on-demand via rpcbind.socket, and even though it actually appears to be the ideal case where something can be lazy-loaded on-demand, simply because most people don't use it, but is installed anyway.

lazy-loading it on-demand is transparent to the client, so there really isn't any drawback to socket-activate it.

To make this work, simply drop The line "WantedBy=multi-user.target" from /usr/lib/systemd/system/rpcbind.service. 

(And while you are at it, please drop "After=syslog.target network.target", too. syslog.target is entirely unnecessary these days, all services get syslog support for free anyway. And I don't see why rpcbind should require the network in any way. It just listens on 0.0.0.0 and AF_UNIX which both are available at any time anyway, so there's no need to wait for the network or anything.)