Yes, commenting is a great strategy if you can manage to consistently write genuine comments -- and I think most people can tell whether your comments are genuine or not. I've had mixed success with this because some authors simply receive too many comments on their posts and perhaps overlook mine. Some authors, no matter how many posts I comment on or to what extent, just never respond to me. That doesn't stop me from continuing to comment, though.
A lot of times, for me, it's better to respond and join in to a conversation already happening in the comments. At least there's a higher chance of engagement there. Engagement is my goal more so than receiving an upvote for my comments (although that's nice too!) ;)
Some of the very popular authors do not look that interested in their commenters imho. Their loss:)
I very much agree with you; they are simply writing so they can get bot upvotes. :)