Generally it has always been a closed beta that is invite only, and I would guess they will do the same thing again this year. It's only an assumption, but I believe they do it so that they aren't constantly bombarded with feedback and bug reports. Realistically if you are going to give the community a beta, it is much easier to use a closed beta. People will try absolutely everything either way, and it is much easier to receive tailored feedback rather than "this game sucks" or "passing is bad" with no explanation or reasoning.
Betas are generally supposed to be for problem fixing, so it's easier to restrict who has access.
