I am not one to say give up quickly for a few reasons.
It could be a case of the right project wrong people. Happens all the time. Maybe no one has found the right angle on it yet. Your name could be Nostradamus Horton or McMillin.
Some properties got left behind in development because there was still plenty of easy build land around and houses were cheap. Times have changed.
I have had success buying a splittable landlocked 20 acres and buying easements cheaply from neighbors.Not such a huge windfall because it is rural and limited to two ten acre lots but still a good deal. It doubled the value of the lot
even without splitting. Actually my neighbor just paid three times what I did for an unsplittable lot.
Anyway, you will probably hit a dead end because of some of the things we have mentioned but it doesn’t hurt to look at it.Even the easy ones are a nightmare BTW. It all depends on the potential endgame and interest and ability for the project.
Double check the addresses I gave you if you intend to start with them. I deduced the addresses from the tax assessors partial map and the position and addresses of the few houses on the mls related to the 5 acre partial.