Other:
I do drop the occasional review, but for the most part, I don't do a lot of reviewing.
There are a few ostensibly different reasons, but I feel they're connected by a common thread.
That being: I feel that my advice is better spent in discussing music and composition in a more general sense or regarding specific topics like perhaps harmony or melody writing as a concept rather than trying to tell someone how to "fix" or "improve" their piece; I would rather talk about that stuff and feel I'm better at "helping" with that sort of insight that way anyway. To be frank, I also always found those sort of posts more useful than what are often highly subjective grievances with a specific piece, from a specific person.
Another is that I don't like to listen to music analytically most of the time. When I listen to users' music, I mostly just listen to enjoy it. If I do, I'll usually drop a like on their YouTube or whatever and if I don't, I usually just move on. I wouldn't enjoy music if I was always in this "critique mode" and as a person who has an obsessive personality, it would be very easy for me to fall into that.
Most of the regular posters here, I like their music and there really isn't much for me to say beyond "Yeah, this is great". I hope that maybe some of them also enjoy my stuff.
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However, I will say there is a final reason, and I know I risk sounding a like narcissistic @$$ by saying it, but I really don't mean to be or think I'm the very best, but it is just fair and honest:
When I started frequenting musicians forums some 20 years ago, I was often frustrated by how the more experienced musicians we all looked up to didn't really give much feedback or help n00bs like myself. However, now that I'm getting to be one of the "old men" with a lot of experience, having made money with it, got into prestigious national programs by the merit of my own work, and now releasing albums with some of the bigger music libraries and did all of this so far coming from a family that couldn't afford to put me in proper music lessons and I was forced to learn most of this stuff on my own over the course of my entire youth and adult life so far...I understand now why many of them weren't so willing to dedicate that kind of time to what essentially amounts to being a free teacher for strangers online.
Over the last five or so years, I've had people send me emails or messages asking to help them make some piece they're working on into their grand vision. The problem with most cases is, at a minimum, I would have to make posts or videos much longer than this, with pictures, custom examples, or recomposing aspects of their piece. In the more extreme cases, which are many, I would essentially have to teach this person how to compose from the ground up.
I would not just have to teach academic music theory and such, but more importantly, I am pouring in my own perspectives and experience — my life with music — in order to truly help these people grow, and I don't think it is arrogance to feel that that is worth something. The "something" doesn't necessarily have to be money, but in the cases of most, money is all they'd have to offer in exchange.