[Geary] Why Geary does not use EDS?

[Frederic Parrenin <frederic parrenin univ-grenoble-alpes fr>]

Dear Geary developpers,

I really appreciate the UI work done on Geary, congratulations!

Pardon my simple question, but I would like to know why Geary does not 
use Evolution Data Server (EDS).
The idea of EDS was to have a common backend shared by different frontends.
It works already for agendas (shared with e.g., Gnome Calendar) and 
contacts (shared by e.g., Gnome Contacts).
From a user point of view, I like this because I can easily switch the 
frontend if I am not happy with it, without reconfiguring everything and 
duplicating the offline information.
I imagine also that Geary devs could really concentrate on the UI work 
if they use EDS, and this is where Evolution shows its age.

Geary devs certainly have good reasons to make this choice, but I am 
just curious what they are.

Best regards,

F. Parrenin