Of course it depends on the context of a company, the ressource you have internally, the seniority of the team …
If you're chasing PMF, a design system will not help you to find it directly, but it can help you to deliver features faster, try things and to not be afraid to throw it away.
In a way, indirectly, it's helping to move forward quickly which is really helpful when you're chasing PMF.
I do think there are a lot of advantages before PMF too.
Somehow, if you need to pivot and throw away you initial product, you can start over a new one pretty easily if your design system is on point. At least, we had this strong feeling when we had to pivot.
It’s a headache to remember return windows for different merchants.