Well, yes.
But the thing that a startup must focus on is not science. It’s raising money so that you can do science. Having a PhD is not necessarily an impediment to raising money, but neither is it particularly helpful.
In fact, you don’t even need a bachelor’s degree to raise huge sums of money, as Elizabeth Holmes proved with Theranos.
Larry Gold (my former boss) is an outstanding scientist, a member of the National Academy with hundreds of publications to his name. He has also raised hundreds of millions of dollars in his career as an entrepreneur. He once told me that investors have only two emotions – greed and fear. Activating those emotions is how you get investors to write a check.
Mastering the science well enough to explain it to investors is fairly easy. They are not interested in the technology, except to confirm that it is plausible. They have no desire to get down in the weeds. Most VCs have technical staff to evaluate claims about tech, and will want some validation from outside scientists – that is the role of your science advisory board.
They do want to get down in the weeds about how they will make a 10X (at least) return on their investment (greed), or how they will look like an idiot later if they pass (fear).
A PhD in biology isn’t going to help with those tasks. Maybe a PhD in psychology, or perhaps a background in the thespian arts. Getting the technology to work is usually the easiest part of getting a startup off the ground. Getting the funds to do so is much harder.