Web developers typically use the .dev extension as a TDL for local development environments. Thus when developing a web app, instead of needing to use “localhost” with a specific port, they’d set up the host files to recognize example.dev as the domain for easier testing.
That has worked fine until now since Google just released the .dev TDL.
It might be time to switch that to a different local TDL; otherwise, your local setting could potentially override an actual functioning app or website with your local configuration.
Granted, it is unlikely to happen unless your website uses the .dev extension, yet, conventions are an important part of a healthy development environment.
With an increasing list of TDLs, the best option might be to start using .development or .local until those get snapped up.