The composition of Platinum players

@Cro_PitttBut demotion protection makes ranking up easier not harder. I agree it makes games less interesting when half the lobby just dies because they don't care, but if all you want is to rank up - that's definitely simpler. With dia4 being put in diamond lobbies since start of this season, getting master is easier than ever (although I still don't think I have the will to put in that many games, as it's still a lot of points to grind).
By focusing on you getting the rank 4's on your team you're completely ignoring the other side of the coin - there's also the same rank 4's in every other team, so 1) getting placement points is much easier (pretty much the "entry cost" of each game is lower because of that); 2) getting KP, even when you're the only 1 alive on your team, is also easier.

I agree that there should not be rank demotion protection - that ruins the "tryhard and sweaty" ranked experience (games would feel a lot different if everyone were doing it, instead of just half or even less of the lobby). But you're wrong thinking that removing it would make ranking up easier - it would be much much harder and higher ranks would have much lower % of players in them than now (assuming scoring rules stay the same).