SPAs are the worst, because companies deploy them to avoid separation of responsibilities and turn every employee into easily replaceable "full-stack developer".

Unfortunately, a lot of people write terrible applications regardless of chosen technology. When this happens to purely server-side applications, the company is forced to optimize them to keep the hosting bill low — a positive feedback loop in action. SPA applications cause the opposite — companies move everything to client-side in order to reduce Amazon bills, and don't care if those client-side scripts are poorly optimized and contribute to global warming by causing hundred thousands machines to spin up their CPU fans.

Clearly, there should be a heavy tax on single page apps. They are

1) addictive — by making more Javascript devs, who in turn write more Javascript websites

2) act as luxurious goods ("Look guys — we have created a new version of our website. It looks so cooool (but loads a bit slow)!")

3) have ugly externalities, completely ignored by most of their creators