Common Lisp is like this. There is a standard, but no changes have been done since then.
On the other hand, it also shows some of the disadvantages - for example, there is no multi-threading support of any kind in the Common Lisp standard, because this was not a common feature at the time the standard was created; neither is there Unicode support. Of course there are libraries that implement these things, even portably (and this being CL, the difference between library and core langauge is minimal), but it's still a point some hold against it.
On the other hand, it also shows some of the disadvantages - for example, there is no multi-threading support of any kind in the Common Lisp standard, because this was not a common feature at the time the standard was created; neither is there Unicode support. Of course there are libraries that implement these things, even portably (and this being CL, the difference between library and core langauge is minimal), but it's still a point some hold against it.