But generally, in the jobs I've had, a "~5000 word mini-essay" is not going to get read in detail. 5000 words is 20 double-spaced pages. If I sent that to a coworker I'd expect it to sit in their inbox and never get read. At most they would skim it and video call me on Teams to ask me to just explain it.
Unless that is some kind of formal report, you need to put the work in to make it shorter if you want the person on the other end to actually engage.
I think what your coworker did was horrible.
But generally, in the jobs I've had, a "~5000 word mini-essay" is not going to get read in detail. 5000 words is 20 double-spaced pages. If I sent that to a coworker I'd expect it to sit in their inbox and never get read. At most they would skim it and video call me on Teams to ask me to just explain it.
Unless that is some kind of formal report, you need to put the work in to make it shorter if you want the person on the other end to actually engage.