Hi Rose! Sometimes really good content gets overlooked. I feel like my curation rate has been a bit of a crapshoot and I'm nowhere near 100% on it. I'm hoping being part of the creator fellowship program will change that, but who knows?!
I think curation sometimes comes down to personal preference; whether or not an essay hops through initial AI bots (just my theory) to actual people; and whether or not the curation quota has been filled--I read somewhere that the curators may have been told to curate less because too much was getting through.
The bottom line is that it remains a mystery and just because your essays aren't curated doesn't mean they aren't worthy.
Also some utter crap gets curated at times, so who knows?!