It's not weird. I suspect a lot of us have no idea, and the author shouldn't assume the average readers know this. It would help to introduce "Fin" before making the claim that it's obvious.
I've never seen or interacted with Fin that I've noticed. Admittedly I've seen a lot less of Intercom over the last 5 years, they used to be on every SaaS site, but it seems there's a ton of competition there now. One of the banks I use uses Intercom for their support but I've never seen an AI bot there, only humans.
I suspect it's very visible for _Intercom_, but not necessarily so for everyone else.