The point is that, if you know the mnemonic (and the surrounding tricks), you can do the exact same exploring by noodling at the keyboard (or the fretboard, for that matter) and be sure to get it right. From there, it's easy to explore other parts of music theory, or to develop one's musical audiation skills.

If that works for you, ok. I have my keyboard connected to my computer, so I am actually at my keyboard as I use the site. Its still nice that I can click around quickly and hear different chords and scales and such, without having to be held back by my limited piano skills.

Could it be improved if it supported web midi and encouraged you to actually use your keyboard? Maybe. (I actually do web apps that do that) But I'm curious why you can't see its value for what it is, which guides learning rather than just basically saying "figure it out on your own."