Your application seems to be a magical unicorn (not being sarcastic!). Most SPA websites I use on a regular basis end up having to reload all of their page components every visit, and frequently on every 'back'.
I'll be really honest here - it helps that it was a direct requirement from day one, and we have financial incentives aligned with handling the offline-only case.
If you handle offline up front - you mostly get bad connection speed wins by default.
It also helps that our app really isn't intended for casual use - ex: we have very few users who just load a page or two and then leave. Mostly they'll be interacting with the page for a duration of between 30 minutes and 2 hours (sometimes as often as once a second).
So yes - very much not a "blog" or "news" or "social media" site, and I think the value proposition for most companies might be harder to sell.
But I personally find it very, very nifty that we can do this at all in a browser. 10 years ago it would have required an installed application, or a port to each mobile platform. Which is sadly still a hard sell in some of the particularly poor school districts we worked with (mostly computers from the early 2000s, if you're lucky a really cheap tablet - like a kindle - floating around)
