Maybe not in the startup world, but because of the popularity of LAMP and the ubiquity of Windows, a lot of people use WAMP (e.g. via XAMPP) as a local development stack.

It's important to be aware of our own cognitive biases: while Linux is the de-facto standard on the server side and the startup scene is dominated by MBPs and its variants (with a good helping of Linux again, though often in VMs), this only represents a tiny fraction of developers. Dark Matter Developers are a thing.

WAMP has been a thing since 2003, with over 12 years of history.

It is the predominant Windows PHP development environment and Apache stack - that has millions of users worldwide.