Server 17 is not new, it is, in fact, very very old, the first European server in fact.

As a result, there are VERY few player who are low level and active enough to do sage. Which means there are't enough people below 80 to fill a sage, hence you are in with those people.

Now, seeing 80s might be a bit extreme, but that's probably a result of population distribution. But I fully expect everyone below at least 70 are in the same sage, so you will be fighting at least some 70s.