Fair enough, you couldn't have something like the vocalist cueing the bassist and the drummer picking it up out of thing air and doing an improvised roll, like it happens here:

https://youtu.be/eg_rgm9VDAw?t=1597

The drummer takes a little bit more than a second to react to it (higher than a lot of stream delays by the way, but I can see how the stacking could mess it up).

That is, however, a bunch of experienced jazz musicians improvising at a high level. In most jams, these conversations happen very often on the next bar (1 and 2 and 3 and 4 and you react on the next 1).

You can see a drummer using the end of a bar to cue the flourish used on the organ in this part, for example:

https://youtu.be/jhicDUgXyNg&t=587s

It takes multiple seconds for the organist to recognize the cue, that is actually for the next bar, then he joins in. This sort of stuff is actually doable just with just video chat and OBS.

Please also note that the product's example workflow is actually worse in that "reaction jammyness" regard than what I proposed:

> The performer receives the track early, and waits the rest of the delay period to play it

This is designed for recording. It sounds more like a studio arrangement in which you have to record your part than a jam session.

> The fidelity of the live stream isn't high enough to record

Seems like an incomplete product. OBS can already record multi-tracks and monitor tracks, which you can leverage to produce high quality artifact recordings. I use to sync them manually using a DAW, but with all those auto-timers, it's a surprise it doesn't do it automatically.