8-ball is one of the most difficult games to handicap. Particularly when there is a large difference in skill level. If players are close in speed, games on the wire works ok. When they are worlds apart, there really isn't any way to handicap it. You can try giving balls up (they stay on table). That somewhat changes the game as it is unnatural to the game to abandon balls, particularly when they are left as clusters or blocking pockets. Sure, the better player will have to deal with it and it's part of the spot. But when there's a big gap in skill level, even that don't matter. 8-ball is just as much a control game as any other. Only having to make 6 object balls (or even 5) isn't much help when your opponent doesn't give you a shot. Don't forget, the better player will also block pockets and play significantly better defense and know complex moves.
It's the nature of the game. Each player is working with a different set of balls but in the same environment. That's unique to billiard games. 9-ball, One Pocket, 14.1 both players shoot the same balls. When there is a large speed difference in 8-ball, the better player is like a giant bully and the weaker player can't get any air to breathe.
You can create spots in other games that could match up an average player with a pro. It's silly, but possible. It's not doable in 8-ball. The IPT was a good example of this. While not handicapped, there were some very weak "pros" there who got hammered 8-0 by medium level real pros. These weak pros are far better than most amateur players.
You can bridge that gap in 9-ball with spots, not in 8-ball.