Dashboards | Android Developers
As you can see, 3.x is for all intents and purposes dead. 0.2% of Android installs.
Following on what Rod said earlier about the 500,000 apps claim, many indie app stores simply do not carry and do not have access to the most popular titles. They'll really need to make sure they get the top of the indies in AppMall if people are to get the apps they really want, but most first-name titles are still Play-only or Play-and-Kindle-only applications, for instance. AppBrain, etc.; those stores are decent for new and upcoming indie developers to put their apps out for wider audiences, mostly, although you'll see a few higher-end titles like TuneIn pop up in them. Netlfix appears to be on AppBrain, now that I've rechecked.
Another consequence of not having Play access: You don't get Google's apps (inc. Play) without sideloading them, assuming they don't get irked by ACL enough to shut off Play access by the identifier ACL reports mimicking Android. CyanogenMod has a gentleman's agreement with Google allowing Google Apps to be flashed onto a CM-powered device so long as they're distributed separately of the CM distribution itself, so they don't have such problems. ACL has neither this luxury nor assurance, and I'm sure the CM team would not be nice about another organization copping their identifier in order to ride their access coattails.