In general, I blog for a combination of reasons, some of which you mentioned: to build a portfolio, to chronicle my learnings, to network. But mostly it's to share things I've found valuable in my own career, in the hopes that they're read by people who might not have heard them before and who will benefit from them. I'm self-taught, and there are many things that I only learned from some blogger on the internet – if I can pay it forward by being that blogger for someone else, that would be wonderful.
As for the likes and comments: I use them as a litmus test as to how much the topic resounded with others – a type of analytics. Some topics will naturally be more popular than others, and it's interesting to see which ones. But beyond that, no, I'm not personally invested and I don't derive any amount of self-worth from the number of likes.
Often I learn new things from the comments that are left (like one here that introduced me to another learning model, which was very interesting) – I enjoy being able to discuss the topics with the readers. If just one person leaves a comment that says something like "Thank you, I never knew about this and it's changed the way I think about it!" then the post is a wild success. It doesn't have to sway a crowd, but if it hits home for one person and makes a difference in their career, then it was worth writing.
Frankly, I don't much care that this is "utterly meaningless" to you – although it does make me wonder why you bothered leaving this comment. Do you make all the authors of the blogs you read defend why their posts "matter" or ask them why they "give a !@#$"? Or, was I just lucky? Be specific please.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.