But since you mentioned this is your opinion, you do acknowledge that these forms of signalling are effective for most other hiring managers, right? Your view is pretty atypical.

Not to be blunt, but your perspective on Google employees is irrelevant in the context of how they're perceived by the broader market. I think that's why your other comment is being downvoted; it seems like what you're saying isn't wrong per se, it's just inconsequential to the job prospects Google employees actually have. Even though you're a hiring manager and don't personally consider Google employment to be a plus, most other hiring managers really do.