It's not exactly the same, but back in the days before "SSL all the things!" became the norm, it was common to have transparent Squid caching proxies on local n

It's not exactly the same, but back in the days before "SSL all the things!" became the norm, it was common to have transparent Squid caching proxies on local networks. If a peer on your network had recently requested a web resource, it was very likely that it was still in the Squid cache, and it would be loaded from there, instead of going to the origin server. Yes, it was a pain whenever the origin server had misconfigured caching headers. The "force reload bypassing caches" shortcut (Shift-Control-R, or Shift-Click-Reload-Button) was always handy. The move to TLS everywhere, which killed these "transparent" (when they worked) caching proxies, made the web much more stable and predictable.