That sounds like your issue is with DRM, not Comixology.
It is the exact same system if you bought the comics from the DC/Marvel app or on a Kindle.
I remember getting into the "1st issue free" extravaganza that Marvel did last year and scored like 50+ hi quality digital issues.
I log into my account in Comixology and look under My Books and there they are, I can pick and choose which to download, etc.
I can log into my account from any device and my books are all there.
To me, that is a plus.
And really, to go back to the original question, if you want to purchase legitimate, digital comics (Marvel/DC) to read, you only have 3-4 options (that I know of).
DC, Marvel, Comixology and Kindle (which you should do because their comic reader stinks).
And they all use the same DRM.
DRM is a whole other argument.