Why does wicked need advanced routing? RTM_GETRULE is only available if
advanced routing is compiled in kernel, but wicked/src/iflist.c tries to
enforce this netlink command to be present.

There is no reason why networking should not start without
RTM_GETRULE/FIB_RULES.

The failure is as follows:
# /usr/sbin/wickedd  --foreground 
wickedd: ni_nl_dump_store: failed to receive response: Operation not supported
wickedd: failed to refresh interface list
wickedd: failed to discover interface state

This is a regression from previous networking setups with dhcp clients like
dhclient or dhcpcd.