Since this game came out, people on here have been saying [insert any rank above gold] is the new bronze.
To those people, I encourage you to make a smurf and see what actual bronze is like. Or just friend a bronze player and watch their replays.
As for afks, in my games when I was in gold-plat it was abysmal. Literally 90% of my games had 2-4 afks on my team. Once I made it to emerald and eventually diamond where I am now, I have not seen many afks on my team. Out of my last 20 games there has only been 3-4. One of them kept coming and going, at least that's what the announcer kept saying. The other 3 were babies that sat in fountain spamming abilities because they're bad. But this is rare for me.
Player skill on a mechanical level in diamond is easily light-years ahead of the level of play I saw in gold-plat. The decision making could use some work, like sometimes members on my team will start baron when the enemy team is all still alive. Or they'll go to elder when we aced the other team when we could just end the game. That said, 70% of the time there is decent to good decision making. Compared to my gold-plat games where the decision making was good 4% of the time at best.
TL;DR diamond is still a rank where players end up if they are more skilled than lower ranked players. Otherwise we wouldn't still see posts on here where people ask for tips on getting out of iron because of how hard it is.
The only counter to this I can think of is the Dev Post Riot made where they said they wanted more people in diamond, or something like that. So at the start of March they changed requirements and doubled the weekly fortitude cap for emerald. That way you can brute force your way into diamond a little easier. I'm not really sure why they did this, but I haven't seen a drop-off in quality with my games. And I'm a support main so I'd be the first to realize when my teammates don't engage on my setups. Like when I was in gold-plat I could be with my team, perma-stun the enemy adc that is all alone, my team wouldn't react, I'd get killed or forced to B and my team would call me a knuckle dragger. However, now in diamond, every single time I stun lock someone, my entire team pounces on them, killing them instantly and I have never been so erect. I can't tell you how many games I've won this way. Catch one player out late game, the enemy team falls apart/gets aced and we win. That stuff never happened in gold-plat because no one knew how to end games.