I mean if you're 1099 you can literally do this.

The argument that W2 cannot benefit from this is that all other expenses are not related to generating your direct economic benefit and are discretionary or not related to your employment. If you are a business, your costs also make someone else revenue and then their earnings are taxed. Likewise, the shareholders of the business then pay their own taxes incremental to the business on any distributions or cash or their ultimate disposal of assets.

That being said, the government at the federal and state level do give you a variety of incremental deductions around costs they think have additional economic value like homeownership, children, and education.