There is consensus documenting why you did something is good (which is what root comment is talking about). Documenting what you did is commonly thought to be a crutch for writing unreadable code.
And as for the third opinion of "the documentation becomes out of date when the code changes", I would prefer slightly incorrect comments to decipher code rather than no comments to decipher code. Doubly so because I can compare the comments to historical revisions.