Google Chrome isn't. Chromium is, but Chromium also tends to download 3rd party close-source blobs from online resources, like the one that turns on your microphone.
Based on the link you provided it looks like it's Opt-Out not Opt-In, so it's not really a bug so much as a "feature" that open source software shouldn't have but google wanted to sneak in. based on this link [0] it's pretty clear that they did this intentionally and only changed things after user outcry. I wouldn't call that a bug.
Sounds like the opt-out tracking Mozilla put in, or the advertisement for that TV show it spammed which did stupid things to text. It would be nice to have a mainstream browser which didn't try to track, advertise to, or shove "telemetry" into users.
It wasn't an ad. It shut down before init if you hadn't manually set an about:config value telling it to run.
It was set up in a dumb way, but people also grossly misreported. The extension was "enabled" by default but did exactly nothing except shut itself down. The behavior was all disabled by default.
https://news.ycombinator.com/item?id=9724409
That's a disingenuous phrasing, though.