In prior years, they allowed other expenses to be deductible for hobbies, but it was done away with as part of the Tax Cuts and Jobs Act of 2017. As for why the cost of goods sold survived but not other expenses, I would guess it's because of how the IRS has come to define the term "gross income" to be net of the cost of goods sold. If you look at Schedule C, the cost of goods sold is subtracted to derive gross income, from which your other expenses are deducted.
