I don’t think you need to think of income accounts as negative if the ledger you use enforces an updated accounting equation that also uses negative numbers, See https://news.ycombinator.com/item?id=40021506
I think the problem with that scheme is that without some notion of debit/credit (or equivalently, transactions that sum to 0), you can't easily tell if your transactions are balancing. Somehow you have to encode the information that Assets are a "left hand side positive" account type, and that Income is a "right hand side positive" account type, which is what the "income is negative" stuff is doing. But now you have to remember which side of the equation the account is positive on.
[1]: https://code.gnucash.org/docs/C/gnucash-guide/basics-account...