The rule isn't weak at all. In fact it's very effective and simple to perform. The only reason it appears not to work is that too many pool players are too dishonest to follow it.
This is false. What you and the rest of the 'anti-pattern rackers' (APRs?) need to learn before you start opining on this subject is a little bit of the history in play, so let me take the liberty of enlightening you a little...
See, back in the olden days the rules used to be that players would rack for each other. Now of course this was a horrible situation because many players knew little tricks for making the balls break poorly and they would use those tricks pretty much all the time. Some were better (or worse depending on how you look at it) than others, but pretty much everyone who played 9-ball for anything significant would do this. And it was hard to blame them because when your opponent is stringing racks together and you're just sitting there in the chair it for some reason doesn't feel quite fair for some reason, so you would do stuff just in self defense. Even the so-called 'good' guys did it.
Of course it wasn't long before all of these tricks started to become known by just about everyone who played a lot of 9-ball, so people started inspecting the rack for stuff. And as more of the tricks became widely known and harder to get away with they would slowly disappear, and then something else would all of a sudden come up and you'd have to watch out for it. There were even some rule changes to prevent certain stuff, which is why if you watch an older Accu-Stats match you'll see the racker tapping the 1-ball (or sometimes banging it loudly) with the cueball to get it to freeze, but after about '94 that was banned because it was believed that helped make the rack worse -- though interestingly enough that somehow became okay again when the Sardo rack came onto the scene. But I digress.
So anyways there was always a lot of back and forth between the racker and the breaker in most 9-ball matches. And once people got wise to the various ways to leave balls in the rack loose there were other moves just about everyone did as well, like racking the balls that little bit higher or lower, or twisting the rack slightly or whatever. And if the breaker didn't like that he or she would complain and then there was bickering and so on and so forth until finally there was rack up there that made them both happy.
Now throughout all of that, the one thing that was never discussed or talked about back then was what we've come to know today as the so-called pattern rack. Except in that case it wasn't a pattern that was designed to make the rack easier, it was designed to make the rack
harder. I'm sure most readers are aware of it, but for those who don't it looked like this:
1
3 5
6 9 7
2 4
8
The theory behind this of course being that the one would tend to go to the top of the table, the two to the bottom, the three to the top and then so on. So if the breaker makes a ball the idea is that he has to move the cue ball up and down to the table on hopefully each shot in order to run out. It worked too, or at least it worked often enough that everyone did it. It was so prevalent that Pat Fleming even included it in one of his instructional videos about how to 'gain an edge' on your competitor.
So now fast forward a few years and over time the game changed from predominately racking for each other to racking for yourself. And now along with that players started racking in a way that was 'good' for the breaker, where say the 2-ball and the 3-ball were at the top of the diamond rather than the 'bad' way where they were on opposite ends, and suddenly people started running more racks. And as soon as they did, all of a sudden up pops this chorus of whining about pattern racking. Hey, they screamed, the balls are supposed to be racked randomly! You can't rack them the same way each time!! But literally ALL of the people complaining about the 'good' pattern were exactly the same people who never once hesitated to put up the 'bad' pattern pretty much every time -- or with an asterisk would 'accidentally' put up a slug rack here or there at various times in the match -- so it's a little hard for me to take them at their word.
So why the sudden change of heart? Why was pattern racking just totally hunky-dory when players were doing it as a defensive measure as opposed to when they do it for offense? It makes no sense.
Unless the thing that bothers you the most is just getting beat, of course. Why then it makes perfect sense.