Ah yes, my bad. /etc/nsswitch.conf (which is also a Linux-ism but BSDs have something similar) supports LDAP. However, an advantage of /etc/hosts is the low latency since its not networked, while LDAP would result to overhead. Still, I believe that would be a suitable alternative. There's some non-bloated alternatives to OpenLDAP, and also an option could be caching.