The benefit of vesting a power in the executive is unity of purpose (regardless of what administration is in power).

The benefit of Congress is slowing and deliberating over knee-jerk decisions.

Having the President initiate and Congress approve plays to the strengths of both offices.

> Having the President initiate and Congress approve plays to the strengths of both offices

Which wastes everyone’s time. If a case merits pardon, amend the law that convicted them in the first place.