I group this tutorial in the same category as the tutorials helping you set up SFML with for instance Visual Studio. Then it could be argued that in fact they DO instruct the user with regards to the compiler.
Regardless... ALL I'M SAYING IS: It would be helpful and much clearer to a lot of beginners who may never have heard of CMake before (like me) to add that short text, less than a sentence. You may not agree, but if it indeed is helpful to people - why do you keep opposing it so much. Because I refuse to believe you think these people should just get out and not use SFML.
Bottom line - the other tutorials have impressed me to no end with the information and how helpful they are to beginners. This one didn't. I have a solution, do what you want with it. Use it (or modify it) and improve the tutorial, or ignore it, arguing that you yourselves already know the information so it needn't be included.