Founders ask for "a senior Python dev." What they usually need is someone to own the three services nobody wants: payments, KYC, notifications. Stack is the cheapest thing to match, since a good engineer picks up your framework in a week.
Ownership of an unloved subsystem takes months to transfer, and it's what stalls your roadmap when someone leaves. We'd hire against the map of what's unowned, not the job title. Most products have a subsystem that only one person understands.