> Don’t you think someone — possibly a user of this site — would have noticed the network traffic?

Given how much analytics garbage phones regularly spew out, you'd have to perform HTTPS MITM attacks to check this – and that's the kind of thing that alters the behaviour of the system you're measuring.

I still don't think it's likely, but if somebody were to find some suspicious code, I have no real reason to doubt that it's doing something like this.