It's unclear if they mean to imply that 1) there are more vacancies of any type than people entering the field or 2) there are plenty of people entering the fie

It's unclear if they mean to imply that 1) there are more vacancies of any type than people entering the field or 2) there are plenty of people entering the field but not enough experienced senior developers to cover the vacant senior developer positions. 1) is a sentiment I've seen frequently expressed, but is not really panned out by the number or type of job postings in secondary hubs outside the Bay (e.g. Chicago). 2) makes more sense, but the article doesn't really address how to solve the root issue when hiring managers aren't willing to hire from the previous two buckets.