Sales is unique because the monetary benefit to the company is mostly objective: If someone closes a $10 million sales contract, that becomes $10 million in revenue.

If a team of developers work together to fix a bug, how would you calculate the revenue value of the bug and how would you distribute that to the team that solved it? Technically the value of a bug is negative because it costs the company, so do you subtract that from the pay of the engineers he worked on it? If 5 people implement a feature that uses a library developed by 5 other people, which was built on the platform team's infrastructure, how do you divide up the commission? It doesn't work.

A $10 million sales contract is objectively $10 million in revenue, sure, but it's silly to attribute that entirely to the sales person just like it would be silly to attribute it entirely to the engineers that built the product or the marketing team that bought billboards.