I don't think you need to find people who are great at both, but you may want to find teams that are great at both. The impression I took from the comment you

I don't think you need to find people who are great at both, but you may want to find teams that are great at both. The impression I took from the comment you replied to is that there should be no front-end and back-end team, but instead 'cross stack' feature-oriented teams, including members who have knowledge of all parts of the stack and can work on all parts of a feature together.