I am currently analysing my page connections and I want to block some tracking scripts and other external URL calls in my network monitor inside Chrome\'s developer tools.>
This is now achievable in Chrome 59 developer tools by blocking respective requests: https://developers.google.com/web/updates/2017/04/devtools-release-notes#block-requests. With this approach it is somehow difficult to turn off all the stylesheets, but it's easier to turn off just the most annoying ones.