People have actually complained in the past. They were demanding Riot do something about ELO boosters. And it was an actual bannable offense but I guess Riot thought they were too big shot to deal with small time boosters. So they just made a rank system that benefits all boosters, changed their stance to "ELO boosting is A-OK bitches," and made it done.
And FYI, dynamic queue does make the game unfair albeit you can still solo q your way up to ranks you deserve but if you are pushing for a new rank progress, dynamic queue just makes you want to rip all your hair out and force feed it to a cute little kitten.
But realistically, the diamond guy is wrong. Boosting and scripting has never been THIS bad. League is losing A LOT of players. There's an upward trend of like 16% I think(?will look for sources I believe it was like 14-16). In Korea alone that's like 28% of PC Cafe gamers. Few of those simply left because of Overwatch but most of them left because the game no longer felt competitive and the game kept rewarding shit mechanic, retard players with no actual knowledge. Instead, you get rewarded for playing broken high burst champs that build tanky or other bullshit like safe assassins that isn't hard to play but makes cool plays rather than actual display of skill. It's not a matter of whether you can win or lose or rank up or rank down. It's a matter of this is ranked. It's about competition. You're supposed to reward mechanics (skill/talent/athleticism if compared to sports), knowledge on the game (which attributes to skill and having knowledge makes you superior over players who are purely mechanical), and the like... yet the past two seasons haven't really felt that way.
Rank dilution with worse mechanic players and lacking game knowledge players have been happening for years now. Dynamic Queue didn't START it, it simply made it way easier to abuse rank system so any scrub can come out with a satisfied rank. The beginning of rank dilution began with implementation of the cosmetic Rank Tier and Division system. Plenty of people were saying back then that more and more crappy players will rank up. And riot is intentionally doing this so they don't lose massive amount of players in lower rank brackets. But that's teh thing. Again this is ranked. You're supposed to reward players for doing good, not doing bad. Yet Riot continues to make FotM champs and reworks like new Malz and Annie ult. Let's continue to make shit easy champs that literally take no skill to play even easier. Honestly having safe Zed fotm is better than Malz's bullshit even if Zed is easier to play.
**Conclusion/TL;DR - don't release rank rewards at all. Utter bullshit. The only people who are crazed about rank rewards are the people who don't qualify for them. Most of us who consistently have been getting rewards don't even care about them. All they have done is encourage elo boosters and scripters to continue abusing the system to get meaningless rewards which don't even matter anymore. Who cares if you got plat border when plat's been diluted down. Sure in about 20-30% of my games when I was in plat 1-5 I get good teammates but the other 70-80% I'm fucked because we got players with terrible mechanics like they're in silver. You got kids going 0/5 in the first few minutes of the game, bitching about no jungle gank and how enemy got 20 ganks when they got none either. You got premades randomly bitching and reoprting non-premade members for simply not being part of the premade... hazing that Riot predicted would happen years before implementing Dynamic Queue.... wow... Most of the "flaws" of dynamic queue are already proven. Doesn't matter if a diamond player comes here to talk shit to silver players about how you don't know anything. At this point if you defend dyn q you're just oblivious. It's like saying "Well I never been hurt or people I love never gotten hurt from terrorist attacks so I don't think ISIS is bad." **
The biggest bullshit is Riot admitting that dynamic queue fucking sucks but basically going "OH we're retarded but we're going to keep Dynamic Queue so we don't look like bigger idiots. But we will remove it where competitive rank matches actually matter because it IS unfair... but it isn't so we are keeping it to help you people at the bottom tier rank up for free." The logic is so stupid. You can hear the hamster spinning the wheel. It's like trying to argue with your gf about how that guy friend who wants to help her get a job, do her laundry and all this shit just wants to get in her pants while she yells "HE IS JUST A FRIEND!"