If there's a ranking system, it better be TrueSkill2. Not this ridiculous Halo 2 ranking system.
TrueSkill2 is undeniably one of the best (if not the best) ranking systems out there. It is very accurate and very fast. Why would you want anything less for a ranking system? It just sucks that game companies have to pay Microsoft to use it in their games, resulting in many games using TrueSkill2 knockoffs that aren't as good.
Ranking systems like Halo 2 (and even Destiny 2) just suck. It starts at the bottom, instead of in the middle and the better you are at the game, the longer it takes for you to reach your 'actual skill level'. Because of this, you're a lot more likely to have people in your game that claim to be your level but are higher than your 'actual skill level' because these people are still yet to reach their 'actual skill level'.
A CSR 20 game consists of people that have a skill level of >= CSR 20 and it will take exponentially longer to reach your 'actual skill level'.
A Halo 5 Gold game consists of people that have a skill level of ~Gold.
It's just not fun to play a game where the enemy team is obviously above your skill level, and then you lose, and then you get deranked. And it's not even the player's fault, it's the game's.
If this was to ever happen in a TrueSkill2 game, it would either be because the enemies had a lucky game, your team had an unlucky game, or because the enemy team was abusing the algorithm (typically smurfing). Either way, it was not the game's fault.
And don't even make me mention the 'confidence level' that TrueSkill2 has. It's amazing. Essentially, the more games you play, the less the MMR change when you win/lose games as the algroithm becomes more confident that you are reaching your 'actual skill level'.