It's true that Linux does this, although my impression is that FreeBSD and Solaris have comparatively stable ABIs. I think they usually keep the kernel ABI stable between minor patches, and change it with major releases. I've never futzed about with e.g. nvidia drivers on FBSD or Solaris, so I dunno.

Anyway, it was definitely just a weird mistake, I'm more intrigued about how varied the Illumos branches/distros are, since I had thought they were mostly just different userlands/package managers, when they seem to have different kernel patch sets and bugfixes...