I think your main point is likely right, but your supporting examples are not. Wikipedia (at https://en.wikipedia.org/wiki/Abraham_Lincoln#Early_career_a...) says:
Lincoln became an able and successful lawyer with a reputation as a formidable adversary during cross-examinations and closing arguments
Likewise, we have https://en.wikipedia.org/wiki/Hillary_Clinton#Later_Arkansas...
She was twice named by The National Law Journal as one of the 100 most influential lawyers in America: in 1988 and in 1991.[123] When Bill Clinton thought about not running again for governor in 1990, Hillary Clinton considered running, but private polls were unfavorable and, in the end, he ran and was re-elected for the final time.[124]
A compliment on Lincoln's cross examination skills does not make a successful lawyer, though he did practice and litigate and unlike the others (that I know about) established case law. As far as Hillary, I wouldn't put to much stock in The National Law Journal - it's like the national dean's list, rising star lawyers, AV rating. What do you really know of her career? Did she take cases of first impression; set case law; argue before SCOTUS; set a record on a monetary judgment/damages; become partner at an AM100 firm or white shoe firm; hold a meaningful judicial clerkship; become a federal judge?
These are all smart people, successful politicians, but as lawyers I'm not sure anything ranks them in the upper echelons ...that certainly doesn't mean they were failures, which is being read into my statement, I think. Despite the thread opposing me, I don't see any merit based support they were the most successful lawyers.
You added the word "most" :) Your revised statement is probably right
Obama, Clinton(s), Ghandi, Lincoln...none of whom were "successful" lawyers, but they all did just fine in politics.
As to your point about laws/code not preventing horrible things...they often times do. But no one is claiming laws always eradicate behavior (they can and have) that's why we put people on notice and create penalties because we know people violate the laws/rules anyway. Say Bill Clinton lying under oath, he was caught and the only one who disciplined home was the Bar of his home state: totally disbarred him. In other cases, the law itself might be immoral -take the British colonial law against Indian's making salt, and Ghandi violating it and being arrested, even after, as a politician he was able to change the law and the norms.