IMO it is just missing a way to turn off quantize and then turn it back on so you can both be on the grid and also swing or be ahead/behind the beat.

As typical though with anything related to web audio, it is neat one off parlor trick to show web programming skill but isn't worth the effort.

A circle is a compact way to make a useless quantized beat but if you want to take this further it will just end up reinventing the DAW wheel timeline. Otherwise, you have to have a sequencer for the circles, and then a timeline and then just get rid of the circles and have the timeline. In other words, a piano roll.

On another level, it is the coolness but uselessness of circular data visualization.