What? Phrasing is very naive.
Everybody wants something. They want people to help the world’s most promising entrepreneurs win in Boston. Taking money adds constraints. Insisting on a move to Boston adds constraints.
There really is no strings attached to the money if you win. You could go to Vegas and put it all on black if you wanted (although the judges would probably sense that was the plan you wouldn't make it through).
P.S. I was on a winning MassChallenge team last year (Rentabilities)
To get cash, office space and a network without giving up any equity is a relatively remarkable thing.
Being in Boston doesn't do anything for them directly. Their indirect hope is that it will compel you to fall in love with the city, and perhaps increase the local economy there, but they don't get anything out of that, and it isn't a requirement.