If a site feels unusable like this it's because you're the not the user. News sites, for example, are SPAs because they want to sell you ads. It has nothing to do with the technology and everything to do with the business using it.
Which news sites are SPA's? I haven't seen that. Most are usable without javsacript, though the experience is diminished and some have such harsh lazy-loading that the images are all invisible. And menus/search may be broken. I've never had a problem with navigation, though.
How are SPA-s and displaying ads related? The reload / page model benefits news sites more since they can generate more pageviews and hence ad reloads. There really is no connections. Devs implement SPA-s because they think it's better user experience (yes, it's hard to get it right).
You can still do ads (and they have been done for decades) without SPAs. In fact SPAs would reduce the efficiency of the ad tracking as the ad JS is now competing for resources with the SPA JS.
The point is if their goal was to just serve news or articles the site would be just thin layer over a CDN serving raw HTML. In order to serve and track dynamic advertisements they build sites with MBs of JavaScript instead.
