It's assumed you at some point talked to someone in the lab, or your advisor, or your advisee, or literally anyone about the paper. If you didn't that's probably problematic. So "we" gives non-formal credit to your community.
I have never heard that as an explanation. That kind of credit is often expressed in foot/end notes, at least in the field I worked in. It is implied that the authors speak for themselves.
Well IMO if you're giving some trivial level of credit someone else, you should use 'we', since you're both 'talking. If you reference them by name in the paper somewhere, I feel even stronger about my stance.
