[quesera]

There are worlds where typography matters.

The web really isn't one of them. But they exist. In those worlds, Arial would be the equivalent of bringing the wrong tools to the job, in front of clients. No one is going to get hurt, but there is reputational damage to consider.

With that said, of course in 99% of applications "firing offense" is a joke of overstated self-importance. And "firing squad" is the same, 110% of the time. Obviously.

[politelemon]

The reputational "damage" would be limited to a small set of obnoxious font snobs whose opinions should not be considered at all, in that catering to their perceptions helps nobody in any useful manner.

[quesera]

Sometimes those people are customers, and they matter a lot.

They're also not wrong. The aesthetic of a typeface is a complicated thing. You have history and precedent to consider, for example.

There are objectively incorrect choices, sometimes.

The irony here is that Arial has always been the substitute because the real thing wasn't available. (i.e. Microsoft didn't want to pay to license Helvetica, whereas Apple did).

So the reaction you're having to the idea of someone substituting the original for the replacement is a bit odd, I think. Maybe you're reacting to the idea of caring. You don't have to care what others care about.