Mobile version of info heavy sites

While I know many people use a mobile for much of their browsing, me included, I assume if people want to view data heavy sites they would flip their phone like I do to get a wide screen that fits.

I think I'm probably in the wrong, I've seen a screen capture today of someone scrolling really a lot of a page with that horizonal view and the site is really broken in that mode, started giving it some attention

I've seen in some live stream building a really cool browser to view multi devices render on one window (and I know the 3rd party SaaS offers that take screenshots and even compare between versions) anyhow I went and search for an open source tool, and it's really poor comparatively, but does the job to show me the light - "Responsively App" if your interested.

I've only did the top menu so far, it's cute, I don't have a vision for it and I'm not a designer and I did it just to check a mark for now, too many things to do... there is always going to be something more important.