To release and promote music, companies spend alot of money. Currently bc of digipacks the album prices are also at record low. They also spend alot of money to promote the digital material on spotify and youtube.
On the other hand for CFS and Brand deals they just cash their checks without spending anything.
The end goal for any business, Kpop included, is creating a loyal fanbase that you can sell to.
Any business will have their main income, and (multiple) side income, and cf & brand deals are the side income. It's nice to collect $1m not paying any expense. But it's nicer to make $5m from a concert, spend $2m, and profit $3m. Second option is better because you have more control over the income source AND you make more money.
In business, you can think of CF & brand deals as affiliate marketing. You help other people sell their product and you get a cut. However, the next step is always to make your own and sell it, because you profit more.