Some users (like me for example) use phabricator on platforms which support newer ssh key and cipher algorithms.

Currently platforms supporting these are:

• OpenBSD - home OS of openssh development - should support newest bells and whistles naturally
• FreeBSD - latest 10.1 relases support these keys - all my phabricator installs are on this platform
• ArchLinux - has latest openssh version in repositories
• probably several others

ssh-ed25519 can be much smaller than others and this makes them more managable and visually recognisable.

According to talk on #phabricator@freenode, phab does some minimal checking of key type and it would be great if it supported these keys, for people who deploy it in such environment.