I agree. Possibly to just give a bit more weight to what they say. So far, I've mostly seen this with Google employees here. Can't remember seeing anyone else mentioning this except when promoting a product.

1. Regarding policy, I think a simple disclosure like this is my personal opinion not that of my employer would be good enough. 2. Indicate possible bias: nope, one should always understand any opinion is biased due to many different reasons. So, unless this is a rigorous analysis of something, this is quite uncalled for.