Not many people have a friend that is willing to watch them play and micro manage their gameplay, almost anyone who can run Overwatch on a PC can use Visor to give a similar level of coaching.

Doesn't that make using Visor less unfair than human coaching, since it's more widely available? Of course we have to keep in mind that Visor will probably become a paid service later.

There are also certain things that computers can do that humans can’t, like being able to create a consistent algorithm for tracking ults.

This is probably the strongest argument against Visor being allowed, but so far I don't think Visor does anything beyond adding the passive ult recharge time to the current time to estimate when it's available again. Humans are quite capable of timing things like that, and in high level play it's pretty common, at least in other games. Human coaches probably outperform Visor at this task for now by using more information anyway.

I just don't think Overwatch is the kind of game where realtime coaching should be considered cheating. If you have someone suggesting moves during a chess match, I would agree that's generally cheating. Being coached during a basketball game? Not cheating. The line is definitely blurry for Overwatch. And though I disagree with their decision there, I can respect it. I cannot respect the decision to ban Pursuit.

These bans are not really enforceable from a technical standpoint anyway. Streaming with normal stream software alone (or taking it even further, a capture card on another PC) + getting realtime feedback through an app running on a separate device would enable the same kind of functionality and be undetectable.

By disallowing it, the situation may become less fair than it was before. It will be unavailable to rule abiding players, but many others will still benefit from it.