I'm a python user and parallelism and performance are not the reason I tried Golang because I had no poblem with these for my use cases. However, it solves the only problem I have with Python which is deployement/distribution: basically your server can be a single binary. Best of all, you can target whatever platform with ease. You don't have to worry about your client having the right python or the needed dependencies and this comes with no effort on your part.

Given that the language is relatively easy to grasp and that the standard library covers all the basic needs of a server application, that alone is a huge win.

Python still has more and better libraries for certain tasks though.