Like I said earlier, I'm not all that familiar with CSGO and I'm not all that surprised to hear that my proposal for segregating games based on skill level has already been implemented.
As for the people who cheat that system, purposefully lowering their rating so that they can score easy victories against- and belittle- less skilled newcomers:
Purposefully avoiding competition against people with the same or greater skill level for an easy victory rather than an actual challenge? There is a word for such a person: a coward.
Purposefully targeting people who are less able to fight back on the same level, and moreover belittling their lack of skill and familiarity with the game at the same time? There's a word for such a person: a bully. (And like the current ads for the latest Assassin's Creed game says: "I'm not overly fond of bullies!")
Yea I never understood why they do that either. I love the challenge of the game. If I wanted easy kills I would've played against bots. It baffles me that these people enjoy doing that kind of thing. Although sometimes it has a purpose, only sometimes. I heard they usually help their friends rank up by doing that. By dominating the other team you give your friend a higher chance to get more kills and score more points than usual. That's just another lame justification though.