The EU has a cap on the work week which you can opt out of, so most businesses 'asked' you to sign a waiver to work at the company.

You can't force people not to work, so you'll have some people who will choose to and some who won't, hence the people who do will have an obvious advantage.

That being said, progressing isn't everyone's life goal and I hope projects like this help create a market that 4-day weeks are the norm. The CTO at my last role was seriously considering this.