Part of it is because the company asks us to. Part of it is because I think it's reasonable to tell people your biases, and it can avoid the situation where substantive conversation gets derailed by "gotchas". If I make a comment about how I think Google Meet has the best noise cancellation of any video chat software, even though I don't work on Meet or anything adjacent to it, it's still a bad look if someone can dig through my comment history and pull out a previous comment about how I work for Google.