It would be good (especially with the replication crisis), but historically to earn a PhD, especially at a top-tier institution, the criteria is conducting original research that produces new knowledge or unique insights.

Replicating existing results doesn't meet that criteria so unknowingly repeating someone's work is an existential crisis for PhD students. It can mean that you worked for 4-6 years on something that the committee then can't/won't grant a doctorate for and effectively forcing you to start over.

Theoretically, your advisor is supposed to help prevent this as well by guiding you in good directions, but not all advisors are created equal.