the main reason why there is such an absence is because 1.Konohamaru is way too young for most of the story 2.due to his age he won’t be part of narutos class and therefore it’d be difficult to write him in all the canon events 3. since he is part of Sarutobis faction by default his existence is kinda problematic ie realistically Danzo is 100% going to kill the konohamaru protag after the thirds death from orochimaru if he shows any talent or skill and the only way a fanfic author can circumvent this obvious plot hole slash danger is either using bad writing and or ignoring it as a whole or giving the konohamaru si buffs or cheats ie making him overpowered another thing is the third is definitely not going to let his grandson go out on missions freely as konohamaru will be hunted down by like every ninja village atleast while his father is still alive so you have a protag who wants to farm up and brush his skills and talents but is unable to due to his status. 4. konohamaru doesn’t have otsutsuki genetics unfortunately and naruto is a story predetermined by genetics and not a story of hardwork overcoming destiny 5. and most importantly for us coomers there is a significant age gap and almost no waifus for konohamaru to go for unless you’re bringing in boruto into the equation and lets be honest most naruto fans don’t like boruto and you can see that in naruto fanfiction by how often boruto is seemingly ignored outside of the otsutsuki alien world building component. this either forces the author to age up konohamaru or make is try to ignore how weird any romance would be. if a fanfiction cannot work without an author aging up the cast then that fanfiction really shouldn’t exist 6. so the problem isn’t konohamaru himself but writing a logical story with a si thrown into his body that even remotely makes sense

okay another point i fergot to bring up. think about danzo and think about asuma. why didn’t say danzo have asuma sarutobi assassinated after his father’s death? one because asuma is washed out and an untalented hack. two because asuma never wanted to be hokage and inherit sarutobis legacy as he had daddy issues. now say you replaced asuma with a version that was talented and not washed up and also had a desire to run for hokage? you can bet your sweet ass that version of asuma would mysteriously be found dead within 3 days after sarutobis death from the sand invasion arc. so logically speaking the reason why alot of naruto fanfics would never use konohamaru as their isekai or main character target is because it’d be near impossible to write it without having alot of handwaving done. that and the age gap. thats not to say it hasn’t been done before.

110% true. You show your genius in Danzo village + a wish to become warchief=you dead. Without tons of plot armor.