You are right, and I was not clear. The point is still the same. If the lsb base lists a glibc version x.x.x minimum, and glibc is up to x.x.x + 3 and dropped some previous functions, distros have to choose the new library or stay lsb compliant and stay with the old library. Of course, if lsb updates it's requirements, previously compliant applications would fail. The solution for this particular situation is for base libraries to maintain a stable API, but they have reasons why they do not want to do that. So, apps and distros just have to keep up.