Answer 1

1. Linux is faster than windows, so by using WSL you're not getting all the speed advantage
2. Linux and windows have different filesystems, and different file permissions, so it might lead to some problems
3. From what I read, GUIs aren't stable on WSL
4. Not all linux commands are available on WSL,
5. You're still using windows, you will not have the experience of a linux system, not even close. You won't gain much experience because you'll tend to solve things with windows and it programs, and not linux

WSL is a nice idea for linux users who are forced to use windows, but if you really want to grasp linux concepts, and knows what it feels like to manually fix problems and change the source code of some apps, it's better to have it on dual boot.