It seems so scary to ship software where you are not in full control over font rendering, because at that point you have suddenly have a million edge cases which you weren't forced to think about up front, but which can come back and bite you any time.
Though I guess with everything running in web browsers it sort of has become the only way to go.
A few days back I tried to tweet various empty characters [0], but the twitter frontend wouldn't let me.
Seems like this person found some new ones. Curious if they will ban them.