Ya people bought and sold 50s on Halo 3, so what. It doesn't make the system flawed. You act like boosting isn't happening in COD already. In Halo you still had to win the game to boost, but in COD you just need to morons with TI.
A progression ranking system is getting old, and many people can agree with me on this. A True Skill ranking system is something fresh to the COD series and many of the people that have played COD for years would be willing to try something new.
I don't think you actually know what the word competitive actually means. More competitive means for closer matches. Just because you aren't experiencing them doesn't mean others are not either. I have had many more close games in LP than in Publics and I have only played about 500 LP games verse the 2500 Public games. LP is a more competitive environment based around winning rather than just goofing off and screwing around like in Publics. LP has a different level of seriousness to some players and they try the best they can against equal to better players. In LP games don't come easy when playing in a game with all Master, you actually have to work for your win and even then you could lose by 10 points verse Publics where you could just solo the whole game and go 100+ without even trying.
In the end it wouldn't hurt this CODG to implement a TrueSkill Ranking System in to some playlists while other were unranked. Halo 3 did a good job at seperating the 2. The people that wanted to try to achieve a 50 rank could, while the casual players could play their Social playlists(basically what COD multiplayer is anyways).
Platinum and Masters are very competitive. Playing against Bronze and Silvers is nothing to me. I have much closer games when playing against Platinum and Masters than I do playing against Bronze and Silvers. Not to mention that most of the people at that low are bad at the game so I would expect someone that has put many, many years into COD to do somewhat well against them.
I played about 5 good seasons of LP and after my 5 placement matches even if I loose 2-4 of them, I am very likely to be ranked into Platinum or Masters. But to get these ranks, I am mostly playing against between Golds and Masters the whole time. Some games are shutouts and others are close.
The difference between Publics and LP is that there are going to be a lot more competitive/close games in LP while in Publics you are more likely to find easy lobbies filled with noobs.
League play can be very competitive, you just have to be high enough ranked to play good people. The skill level of the different divisions are generally as follows; iron = bad player, wouldn't be able to hold a 1 kd in a normal pub match, bronze and silver = normal public match player, gold = decent public match player through pub stomper, platinum = pub stomper through entry level competitive player, master = veteran competitve player through pro status. Of course, there are always exceptions. Sometimes people just get lucky and get placed highly or cheats and ddos' everyone, but generally the ranks are fairly accurate.