I believe implementing something to prevent higher leveled players from slaughtering low-leveled players would be a better solution to the above issue; something such as a level gap limit.
I think that would severely limit my options, as I'm about 11 levels over the second next highest player (who is a Friend, so I won't attack them). >.> When I hit Brawl all I can see are people over level 47 anyway, and I have to actually take time and search out other players to attack. I already have a hard time locating bottles because of that restriction alone. I personally don't touch anyone below level 40, since it's usually not worth my time to attack for such a low amount of BP.
I think players that are higher level have earned their level fairly enough, anyway. There are many types of ways to play the game, and it is still possible to be a lower leveled player and give higher level players a hard time. I've seen defenses of lower leveled players that have made me second-guess my own attacks. Some players trade all of their STA for ATK and/or DEF at the cost of their levels, and are seriously good brawlers as a result. I've been on the receiving end of those attacks, and I can't take anyone lower than my level lightly. Some players have higher STA at the cost of ineffective brawling, but level up faster than everyone else. If players want to pick on level 5's, let them at the cost of low earned BP. If they want to challenge themselves with harder brawls with players closer to their level, they can do that too.
With a level gap in place, it would be super hard for high level players like myself to even dream of doing things like the Battle Royale Event going on right now, since the majority of players are in the level 40 range. It'd be punishing for players who spent time (and let's be honest here, money) to get to a high level only to have their efforts go to waste because no one is in their "level range" to brawl, and they miss a chance to participate because of it.
Just don't punish the way the players play their games, is all I'm saying.