I recall some composers notes such as 'with great vigor' or 'like raindrops' on sheet music. Midi step sequences would have a hard time representing the "emotion" some composers are looking for.
Remember Roller Coaster Tycoon (2 or 3?) where you could ride the coasters you designed in FPV? Can't wait to induce motion sickness without ever leaving my desk.
It's interesting to compare the site opened in Chrome vs. Safari. I count 12 features desktop Chrome supports that desktop Safari does not (on El Capitan). A mobile comparison would be intriguing as well.