Use spotlight (or Alfred) to open an existing chrome tab
There is a workaround that I use. And it's not that hard. It's called "Nativefier". 


  Nativefier is a command line tool that allows you to easily create a desktop application for any web site with succinct and minimal configuration. Apps are wrapped by Electron in an OS executable (.app, .exe, etc.) for use on Windows, OSX and Linux.


So what this means is that you can create a app(that can be added to you're dock) for one webpage in Chrome for example. So you can easily use Cmd+Tab to switch apps. You just need a bit of 'command line' experience to achieve all this.

Full tutorial can be found here; https://www.npmjs.com/package/nativefier