A lot of time the business person on the team brings two things - 1) translates the tech into “business person speak” which is actually important for raising money AND getting customers excited and 2) they bring a completely different set of relationships that can help commercialize the product.
Also important are translating the business speak back to the startup - how do fund raising processes work? What do all these documents actually mean? Why do these terms in the contracts with customers matter?
This all matters and a single person on the team playing that roll at an early stage can impact things. Just make sure it’s a business person with lots of relationships and experience doing similar things... “business” is general, so make sure it’s the right kind.
I get that communication and networking are important skills, but I wish the business-speak people were valued either equal to or lower than the actual techies, given the respective hours and efforts to the product.
In funding rounds, VC's themselves have enough experience to avoid accepting unreasonable terms, so a portfolio founding team with no background in business is not a problem for the VC and means one less name on the cap table and/or less burn. The same cannot be said of a technical founder, for whom a a business-savvy adviser (either as a cofounder or adviser) may be the thing that prevents them from getting fleeced by an early investor who is unscrupulous or undervalues the business.
None of this is to say the advice is given maliciously. Just that it should be taken with caution normally due to financial advice from parties with financial interests in your behavior.
That said, there is some business work to be done - determining if you have a viable business. Cool science is a great and all, but it’s not a business if people won’t pony up the dollars for it.
And once you know the science works there is a ton of business work to be done, especially with medical products where reimbursement can be really complex and require a year or more of work to get ready for launch. And reimbursement can make or break a product.
Of course you don't _need_ a business person in the team, but recommending to go without one is basically playing the game in hard mode (and exactly the opposite advice you would give a normal tech company). I'd even rate it as more important in a biotech setting to have a good business person on board where the funding power dynamics are stacked even more against you than in normal tech.