I understand how you feel about certain members leaving DE for Doriath, but if you want to talk about loyalty you can also look at it this way. Adisku, Elessar, and Kristie were all originally from Doriath. You can say they're being loyal to their old clan. What if DE died one day (God forbid), and you joined another clan but then weeks/months later DE is being revived, would you stay in the new clan or return to DE?
Btw, I'm also loyal to DE as well as you. You don't see me with a Doriath tag