Whoever had early access will be busy writing plugins to ship with the engine.
You're kinda proving their point here, though. That's exactly the advantage. But then again, that's obviously gonna happen -- making MZ an open alpha wouldn't have been particularily helpful in alleviating the stress of no plugins, so they gotta pick a handful of developers that they deem fitting for the project.
If you want to be one of them you need to prove several things; not only that you're talented, but that you're reliable, easy to work with, you'll be in an advantage with a solid collaborative track record, that there's a good relationship between you and the team to guarantee nothing leaks, etc.
The advantage is, imo, absolutely fair. You wanna be on that group, you gotta work harder, lol.
I personally blame my lack of success in certain areas entirely on me. There are several things on myself that I have to work on and improve before I can prove I'm a reliable artist for some sorts of projects.
I've had chances to work on some pretty cool things in the past and I busted them, so I know I gotta work on that. So, I don't know, take it as an opportunity for self improvement and don't be bitter that you weren't one of the 5 selected team members for this, being a good programmer is only a small part of the picture and logistics also play a big role.