> In addition, it is best to use code navigation simply in a web browser

How do you define "code navigation"? It might've got a bit easier with automatic highlighting of selected symbols, but in return source code viewer got way too laggy and, for a couple of years now, it has this weird bug with misplaced cursors if code is scrolled horizontally. I actually find myself using the "raw" button more and more often, or cloning repo even for some quick ad-hoc lookups.

Edit: not to mention the blame view that actively fights with browser's built in search functionality.