LXC lets you use cgroups, i.e. setup memory/cpu/IO limits per container. If you setup MySQL with more than database, you can't do that.
Also, we DO use LXC and SUPPLEMENT it by something providing security such as GRSEC (in the current version in production at dotCloud) and AppArmor (with docker) :-)
if you do use apparmor and grsec (as in RBAC's part of grsec in particular) it's probably acceptable, but I haven't seen it mentioned on the website - and people figure, they'll just use lxc "and be safe".
LXC lets you use cgroups, i.e. setup memory/cpu/IO limits per container. If you setup MySQL with more than database, you can't do that.
Also, we DO use LXC and SUPPLEMENT it by something providing security such as GRSEC (in the current version in production at dotCloud) and AppArmor (with docker) :-)