What I can't stand is typing "f" then pressing "<Enter>" in the url area of a browser, and the browser interpreting the url as "f" because "f" won the race against autocomplete's return value of "https://foo.com". Just hand "f" off to autocomplete and navigate to whatever the return value happened to be.
Of course it's a browser, so I'm sure someone could exploit my desired behavior to somehow mine cryptocurrencies in a hidden iframe.