I'm fairly sure it's this:

Frequent flyer programs have different mileage requirements among different parts of the world. Sometimes it may be better to fly to a country considered part of Europe. Other times, it may be better to fly to a country considered part of the Middle East.

Most airlines seem to consider Turkey to be in Europe. Are there any that put it into their Middle East region (as defined by that airline's program, which may not match generally recognized geographic regions)? ]

Editorial comment: I can see advantages in flying to "Europe" from another part of Europe, then flying from "the Middle East" to Asia. That would work if one country can be in both, depending on the airline ...

(I don't know of any, but that doesn't mean there aren't any.)