Blame it on the ADD, baby 
(I'm the pink pony in the back)
You know, I think I'm a combination of semi-relevant /total engagement. (though all start off with total engagement intentions until my tangential tendencies take over lol ) I almost never do the nice post thing - if I like something, but don't have anything to add (or don't have time to comment), I just give an upvote. I never upvote anything I haven't read though. (I end up upvoting but not commenting on a lot of your posts - you put so much thought and effort into your content, I consider it almost an insult to leave a 'nice post' note on here...many times I MEAN to comment but don't get around to it)
I kind of laugh when I read 'I only curate manually" - because I forget how many people have pet bots to do it for them. Doing it any other way isn't an option for me. I can honestly say rewards are the furthest thing from my mind when it comes to 'curation'...I don't even know how that math works. I really should learn though! Sounds like it could be lucrative ;-)
I hate to blame stuff on my ADHD (ok, I do though, it's a real challenge!) but I tend to be 'working' on a few things at the same time - and will often have 20 tabs open - many of them Steemit posts I've read and want to comment on, or posts I intend to read. It can take me a ridiculously long time to finish a comment on someone's post because of me being me (long winded and easily distracted even when I don't mean to be! ).
Sometimes I'll spend a long time working on a comment - and end up deleting it - for any number of reasons.
I rarely engage as much as I want to. I also get overwhelmed by my feed - and tend to only really engage/look for posts from a few people who I sort of 'feel comfortable' around? (if that real world analogy makes any sense on here lol). Then, when I do sift through my feed, I remember there are so many other people I'm following - with great content - that I forget about.
This is already huge and I had a lot more to say LOL. But - part of the reason I left Steemit for a while was because I was overwhelmed and too focused on how I could make money or find a niche or find time to be as 'social' on here as I needed to be successful...I hate rules ;- ) So mostly now, I treat Steemit like a hobby, and if I eventually can organize life enough to generate some income - that's a bonus. But I'm sure there are others like me - who want to engage more, but can't for whatever reason. That way of thinking - that we MUST do anything can be counter productive at times...we all have to start somewhere - and who knows, some of us who don't post or comment regularly could eventually become 'pillars of the community' - or maybe we just remain as 'seasonal visitors' ...community is essential, and it's part of what makes Steemit so awesome. That said, for those of us who see it as an outlet or sort of escape from the daily grind - too many expectations could be off putting...a welcoming community is nice for all...a gated one, well...it's nice for those behind the gate ;-)