> * Don't give orders ("Do this", "Do that") to your colleagues, since they are not your employees, and it doesn't help promote learning & growth by not exposing the reasoning behind the demand;

I think this depends a lot. I do "readability" reviews at my company to make sure people apply good coding standards and adhere to the coding guidelines that we have. A lot of these are very "mechanical" in nature and when I am reviewing changes that have obvious coding standard mistakes I will write comments like a "linter" would. One of the most common examples:

> Use descriptive ("Uses") rather than imperative ("Use") style for function docstrings. See: <url-explaining-docstring-guidelines>

I think this type of "giving orders" in reviews is fine as long as it's clear this is an obvious misuse/misunderstanding/miss of the readability guidelines. For any other kind of comment I'll phrase it differently ("Is there a reason why you did X? I think doing Y might be more appropriate because <reasons>, what do you think?", etc) but for stuff that linter should've caught I don't think it's necessary to be verbose and "sweeten" the comments too much.