If SPAs had better perf than MPAs, I can assure you Amazon (the store) would be an SPA. But SPAs are notoriously slow, specially if built with React. Amazon tested React and it was too slow for them so they kept using Java for SSR + jQuery. I think they removed jQuery recently, but keep using the same approach of SSR + sprinkled JS.
As for dev complexity, I'd be very surprised if that was the case. Are taking into account writing the backend code or only the frontend? What about client-side data caching? What about spinners? What about mismatched version of the app for users that don't close their tabs all day long? Etc. Etc.
Yes I know all problems with SPAs have solutions. But that's the point the article is making: you have to solve it.