It's being proposed in order to maintain quality of life. No one wants to be overcrowded. This is a sane solution: collectively agree on the maximum tolerable population. Then it's down to individual responsibility to obey the norms of one's society.
Edit: unless you're Swiss, your opinion is irrelevant. Swiss voters have a right to decide how they want to live. They're not beholden to EU laws; they can make their own sovereign decisions, and everyone must respect that.
Edit: unless you're Swiss, your opinion is irrelevant. Swiss voters have a right to decide how they want to live. They're not beholden to EU laws; they can make their own sovereign decisions, and everyone must respect that.