There is a pretty substantial risk that it would have the opposite of the intended effect if this solution was to be implemented. People who are motivated by easy reputation gain will not stop posting low effort answers until the reward is so low that they do not even think it is even worth writing a low effort answer. If we make the prospective reward so low that it isn't worth writing a low effort answer, then it stands to reason that it would not be an incentive to high effort posts either.
Moreover, those high effort posts may stop being worth the effort well, before the low effort ones do, so instead of just getting fewer answers overall, we would get a higher proportion of low effort posts to high effort posts if the limit is too high to stop the low quality posts.
Moreover, once you reach the limit the system would stop you from earning reputation at later dates, which discourages writing answers of lasting value in favor of answers which help you reach the limit immediately. That would probably still be the easy low effort posts.
To demonstrate the problem, suppose we have two posts submitted on the same day. One mediocre answer manages to get 25 votes during the question's prime, and another much answer is a little late because spending the effort took a little more time, so it only manages to get 20. At that point the net effect would favor the user who spent more effort slightly, by making the early user's score less inflated by means of comparison.
However, now we have to consider that the network aims to be a long term archive of questions and answers: Ideally we hope for everybody to visit that question to find its answers in perpetuity, and continue to vote upon the questions therein with the hope that ultimately, the best answer will rise to the top. It's all in the tour
Now we also have to consider how we reward a person over time for writing an answer that will beat worse answers to the top. Both answers have already exhausted their reputation limit, so if the better answer was to get 10 extra votes later on and the mediocre answer was left to stand where it is, now the better answer would suffer greater disadvantage (-100 vs. -50), and both posts would still be rewarded equally for the amount of effort put into each.
Now the difference with the daily cap is that it isn't it is relatively difficult to reach and rather than being post-bound it's time-bound and resets itself, so even if by some freak occurrence you do get 200 reputation on a single post, you still stand to get however many points there may be the next day.
Granted, perhaps some people do not care so much about the reputation system but those people will not change their habits irrespective of how it is balanced or what kind fof answer they prefer to write, so it is almost as if they may as well not exist for the purposes of balancing the reputation system, unless it can be demonstrated that they exist in unequal proportion to those who are motivated by it.