The isolator most likely won't help. Odds are the pickups on the guitar are picking up the extra noise from the pedal, thus it will always pass the noise along the entirety of the chain, isolated hub or not.

I have no idea why we don't have ADCs at each instrument (if required, otherwise just send the digital output) and DACs at the speakers/amps only with a fully digital mixing and distribution chain/network... it seems silly to be stuck on analogue audio distribution and mixing networks where these things are still problems.

I'm sorry people are downvoting you without explanation... I used to think the same thing myself until I actually got into music and the engineering behind why things work.

The reason why we don't do that is acoustic and electrical coupling. Sound is AC, and because it is alternating we have to deal with impedance matching. air to physical objects actually has a poor impedance mismatch because of the difference in density. Electrically with pickups, when one system has a poor impedance match to another system some really interesting effects can occur. When you overload a downstream device sometimes you can produce interesting interference that just happens to produce harmonics that are musically pleasing to the ear (3rds, 4ths, 5ths). Electrical guitar amps are a great example of this; you can actually design a tube amplifier to produce even or odd order harmonics by the electrical structure of the amp.

It's the "less than perfect" analog devices and their complex interactions that make what musicians to refer to as "tone".

Fortunately there is actually an alternative: it's called balanced transmission. The standard for audio is unbalanced unfortunately. But essentially you get the best of both worlds: noise rejection from third-party sources yet analog transmission and coupling. Ironically most digital transmissions eventually travel over an analog balance transmission.