alt Hacker NewsThat depends entirely on how much needs to be downloaded for each round trip.
A lean website can work just fine on complete trash connections like GPRS or Comcast without incremental loading. Web developers are not incentivized to make lean websites.
SPAs add unnecessary complexity -> increasing page weight -> making finer grained incremental loading more important -> requiring even more code. It's a self-induced problem.
As a corollary, McMaster Carr is often used as an example of a website that didn't fall into the SPA trap, and customers greatly benefit from that [1]. The front page weighs about 14 MB with all of the images, but the loading experience is great even with network throttling simulating a poor connection. There is a good reason the site has this reputation.
Overengineering is the true root of all evil. Web developers cannot learn that fast enough.