I really don't find the evidence agreeing with such a broad statement.
Here you go: https://techcrunch.com/2014/04/14/sf-housing/
All the numbers and data have gotten worse in 2014.
Oh yeah, and SF's onerous rules are making it even harder to expand the housing supply: https://www.bizjournals.com/sanfrancisco/news/2018/12/19/hou...
Not arguing that housing is expensive, just that "There is no amount of money an owner could pay an employee within the economics of a small business" is an extremely broad claim and obviously wrong.
High-paying small businesses, especially when employees do not have children to support, do fine. It's not like you see mass retail vacancy in SF.
At most you could claim: "A worker in food service with family will not be able to afford living in SF, as a restaurant will not be able to pay the needed salary without raising prices above what the market will bear"