I don't know if I necessarily agree with the points in the article but I do agree that SPA's, especially modern ones, are probably better than MPA's. Client side routing is generally going to be more performant since you can minimise bytes over the wire or pull from a client side cache, preload link data etc, not to mention you can maintain state across navigations without hacking around local storage.

Modern SPA frameworks by default do SSR so it's not quite like serving index.html and bundle.js from a cdn. But for actual web apps you can do that and it works fine.

I don't really see the advantage to not using one of these frameworks today. Templating HTML in something other than Svelte/React/etc feels a lot worse in basically every way. And you get seamless reactivity. Frameworks like Solid and Svelte are really close to vanilla-js performance and their bundle sizes are quite small. Not many downsides imo, even for static sites.