I'm definite you're just doing what's right, so the intention of leaving an answer is to demonstrate which reviews are SE-acceptable, as far as I may have understood, and what you currently feel (the unease of being harpy as a common commentator) is just the feeling I used to have.
When should I comment?
You should submit a comment if you want to:
Request clarification from the author;
Leave constructive criticism that guides the author in improving the post;
Add relevant but minor or transient information to a post (e.g. a link to a related question, or an alert to the author that the question has been updated).
I'm not that active in here, but I'm a nitpicky (emphasis on the negative connotation) and zealous reviewer in chemistry.SE. (Haha, and I love bragging about it) I have a different point of view than that of yours.
Stack Exchange is a community where people are here to help people, which isn't only answering questions. Editing is encouraged, not to mention commenting. Reviewers are awarded with three badges. For voting, we have
vox populi. What does that mean to me? It means that reviewing is a goal SE creators had in mind which could actually matter as much as voting. That's the sole purpose of a badge: To summarize how passionate (or cool as in asking or answering) a person is about a specific SE community. Instead, I have a couple of pointers to leave:
A review must be a review, a reviewer a reviewer:
I have no idea if what I wrote above even makes sense. But I know one thing:
I feel, guilty, when I click "no action needed" when reviewing. I just became devoted to SE in a month or so, and have been reading much about it, either in per site metas or meta.SE. When you're reviewing, do an upvote or downvote, leave a comment, flag, or close. Come on! You can do one of them. The points in reviewing are:
- Review carefully. "Not reviewing at all is better than a rash and reckless review." (Paraphrased from here.)
- Don't overreact. There is a boundary between being a caring and sympathetic yet disciplined and serious reviewer and being a pessimistic one who closes anything in touch because in the furthest sense of the question lies proofreading assistance or dictionary look up.
- Consider excessive "politeness". It's better to say "you probably should provide your research into solving the problem yourself." Instead of for example "you must show what you've done or we'll close this." I figure out the latter isn't impolite, but gives a "shouting" connotation as the OP sees the comment. And I also figure out auxiliary verbs of speculation do the job the best way. :D
What you're currently doing isn't discouraged at all. This is the disciplined way of reviewing. If you feel (And I'm saying feel, not be certain) a post can be improved or the OP has to be notified, just do it. The problem is when you don't do these. I'm telling you to comment more and often, as long as comments are intended improvement requests.
Don't get bothered with attacks:
It's crystal-clear that no two people are the same. To make matters worse, people are of different moods when visiting here. It's morally feasible for a user to visit here after s\he has just found out to have blown up their geometry final exam. To make matters even worse, when new users are unfamiliar with the rules they should abide here, and see such comment when looking for an answer eagerly (maybe looking for someone to do their homework, at times) they could feel hurt. To make matters even worse, non-native speakers are a lot to come by. They may misinterpret what you mean pretty easily, or they might use words that have implications they aren't fully aware of.
So you see, the case of ELL attacks can be more serious and more common.
There are but a few points to this answer as well:
- I'm fully aware that you already knew these. But I wanted to say that "don't hesitate when you're on the right path".
- I wanted to repeat that "being perceived as picking on people" is never the case with any who are familiar with SE rules and are in good temper at the moment.
- There aren't any problems with clicking "no action needed"; as much as I never had any intentions to offend anyone. If you feel offended, be kind to accept my apologies and care to comment.