yes :D that's true, for me it's mainly I just like linux :D ...
And why Linux and not Mac?
I don't have problem with Windows. Well, file-system's case insensitivity might be the only one in rare cases.
Use what you know the best and feel comfortable yourself with. Professional web developer should use both Windows and Mac at least for testing and understanding user experience, there are also some tools which are available only for Mac/Win.
If after Linux some nice distros are ones like ElementaryOS. I only use MacOS and iOS devices for my development work, for me it's the systems, performance and is the tools that are only available on Mac and iOS devices. Apps like Sequel Pro, Textastic, Transmit, xCode.
Look at what you use for software/tools and what will work best based on that.
What the others said plus:
Espescially if you're writing code for the web, more often than not you're going to communicate with servers that run something in the realms of Unix. So depending on what you do, you might have an edge on Unix-based operating systems like Linux and OSX.
The best distro for web development is a matter of preference, since one can do anything in any of them. My preference is debian.
As for switching: If you feel comfortable working in windows, don't bother. If you don't, then give it a try. I think that both can be used to create almost anything but I feel that linux is a bit easier to set up and more versatile.
I don't think that Linux is better than Windows. The only thing which I dislike about Windows is the case-insensitive FS. Other than that, use whatever OS and tooling you like. Go for Windows, Linux, macOS, BSD, Haiku, Redox, Plan9,......
I use Windows and Linux for Web Development. On Windows, I use WPN-XM, git, Webstorm and Chrome, on Linux I just install the tools from Portage and use git, Webstorm and Chrome. There really is no difference :)
I even prefer the GitHub git-shell on Windows, but that might be because I am too lazy to configure something like that on my Linux :D