It's easier (or at least different) to say to your friends "let's go to a phone free bar" than it its to say "let's go to a bar, phone-free".

In the first case, a third party came up with the idea, and you are subjecting yourselves to their idea. In the second case, it's your idea, and your friends are subjecting themselves to your idea. Really if you are proposing, there's always a bit of "your idea" there, but the "blame" can be shared with someone else who's not in the group.