I get that, but for the transaction costs for a house sale I think it is applicable to the net worth - whether now or in the future they will be required (the percentage assumption might be different) and that is an amount you will never realize - doesn't matter if values go up or down the costs will be there. Its not the same as deferred maintenance because you may or may not have to spend that - you may decide to walk or sell your car - although to be honest I have a couple of accounts for home repairs, cars, and vacations that I add to each month and don't include in my net worth.
Maybe, but you might never sell the house, so you may not have those transactions costs. And, like taxes, costs can be mitigated. You could FSBO, avoiding a commission. You could negotiate buyer paying all closing costs. You could owner carry.
It just seems to me that you should either count everything as it is today, without trying to incorporate future expenses, known or unknown, or you should count future expenses on everything as best as you can (such as the taxes on stocks example, estimating based on your projected income tax rate when you will be liquidating them, i.e. during FIRE).
If you have accounts that you don't count in Net Worth (and house, and whatever else), I'd argue you aren't doing a net worth calculation. You are calculating liquid worth, or portfolio worth, or something like that (would have to know more about what you do, and don't, count in order to more precisely name it).
EDIT: I have no problem with you doing it however you want, I just like discussing this stuff. :)