Your post sounds like "it sounds bad, but it's no different from what others do, so it's not that bad."

I would put it more like: it sounds bad, and it's no different from what others do, so they're all that bad.

The fact that they're working around an API limitation doesn't make this better, it just proves that they're up to no good. The whole reason there isn't an API for this is to prevent exactly this sort of enumeration.

It's clear that companies will do as much bad stuff as they can to make money. The fact that you can do this to work around extension enumeration limits should be treated as a security bug in Chrome, and fixed. And, while it doesn't really make a difference, LinkedIn should be considered to be exploiting a security vulnerability with this code.