This is mostly just food for thought, and spoiler answer: No, but its real close.
To really answer this question, you first have to ask yourself what you value most in an MMO, and how many of those factors does a game have to have before we can label it an MMO in the traditional sense.
Let’s start with the easy stuff.
Massive: A large number of players need to be around, more than a large FPS map or private Minecraft server of 64 or 128 players.
Multiplayer: Not only must a larger number of players be around, but that should mean something critical to the game. If you can get 90% or more of the experience without interacting with others, the game fails here.
Online: This one is interesting, because at first you think this is simply about connecting to a server, but does asynchronous activity count here? Or does ‘online’ mean two people are online and interacting in real time? A dungeon run is real-time, you selling something on an auction house is asynchronous. How much of the core gameplay needs to be real-time to count? Does it at all?
Let’s look at how I play CoC/BB. I run a ‘clan’ in both, the CoC one has 50 accounts, the BB around 30. In both games we have regular, guild-wide activities (Clan Wars and Operations), and in both of these activities we spend a solid amount of time helping each other out and working together to win. One is group-based PvP, the other is group-based PvE. Chat is very frequent and lively, and Reddit/YouTube is often referred for strategy or game updates.
Personal and guild-wide progression is a main focus of both games, and both games are frequently updated, often with content that adds more progression. Both games are played by millions in one ‘world’ (you can potentially interact with anyone playing), and minor solo PvE content aside, everything is multiplayer.
Basically, the way I play CoC/BB is more like playing an MMO than how I play FFXIV today with my wife, where we duo almost exclusively (random fate groups and dungeon runs aside). I’m more invested in CoC/BB, I’m more into the community of those games, and I do more massive, multiplayer, online gaming in those titles than in FFXIV.
Again, the biggest disconnect is the asynchronous difference, and the lack of a true ‘character’ to play in CoC/BB, although that last one I could argue is no different than flying a ship in EVE. In CoC/BB I’m the chief (pilot) of my village (ship), fighting against other chiefs (pilots) and their village (ship)*.
*Insert easy TiDi is asynchronous gameplay joke here.