This is an unfortunate over simplification (for both responses). Argument towards invalid data is stating an assumption- "Most of our experiments have nothing to do with each other" < that isn't a scientific method. Its simply an opinion that you are taking no effort to gain clean data - meaning the truth.
If a scenarios exist that can invalidate your findings, then you use every scientific method to avoid them not enable.
"Pinterest is a pretty big website, so it's unlikely that our experiments affect each other in ways that'd make our tests invalid." << This is the very reason why you will have an attribution problem.
If a scenarios exist that can invalidate your findings, then you use every scientific method to avoid them not enable.
"Pinterest is a pretty big website, so it's unlikely that our experiments affect each other in ways that'd make our tests invalid." << This is the very reason why you will have an attribution problem.