The founders of the company can come from a lot of different backgrounds: they might be marketing folks, or sales folks, or just someone in a different industry altogether who want to build their own organization. They might be money guys trying to cash in on a hot industry idea. So it's pretty common in the early days of a startup to have a huge disconnect between the organizational vision and actual technical capabilities.
On the other hand, sometimes the founders are very technically savvy. The best situation is when the founders have both strong technical skills as well as "business" skills.
In the early days of a startup, the technical resources can get stretched very thin. So they may be playing lots of technical roles compared to working in a big shop where people can focus on a smaller set of tasks. Also, startups are typically short of cash and sensitive to how much runway they have, so it's common for them to pay less. This means that they bring in people who are building their technical skills, or trying to prove themselves in the industry.
The stereotype is young guys who want to program all day in the office, working for peanuts, sleeping under their desks at night.
As an organization grows, there is potential for people with real talent on both the technical side and on the "business" side to emerge. But sometimes the organization needs to add the talent they need as they grow and get more money.
Scaling is just one aspect of that growth. There are other important technical capabilities, such as harnessing advanced technologies, creating a compelling user experience, and (nowadays) handling huge amounts of data.