Honestly I glance at this thread growing and I think it needs to be deleted and republished with new criteria regarding what is bad matchamking.
Yesterday had following two games:
1. my longest game so far - my team collected 402k, enemy team was around 380k. HOW - my team despite doing ok in 1v1s, totally lost the laning phase, losing all 3 guardians before we even took down 1, but enemy team was equally bad at taking down walkers and gave us comeback.
Pinnacle of the skill - we had rejuve (I did it solo) and 6 people alive, enemy base open guarded by 1 person and 3 people spawning back in 30 seconds) -> my team went farming jungle

Idk if they were trolling or what but eventually I almost solo took the enemy base and on my 3rd attempt finally my team joined me, we won.
Long story short: people have 0 clue on micro / macro nor have idea how to take fights, as soon as they see more then 1 enemy hero, most back out even though we still have numbers advantage = noone is ready to "die for the team".
p.s. this was so funny as moments before this game started I watched YT video explaining why nub games takes forever to finish (which in my experience is exact opposite)
2. one of the fastest loses ever - my team had 60k disadvantage by 20th minute (I think game ended before 25th minute).
Had 3 people - Silver, Wraith and 7 - who had 0 clue how to lane, they in total died almost 30 times. Most of the team ended with 15-20 deaths and <5 kills, some of them had <3 kills or 0.
3 people had mics, they used them only at the end to crack some funny jokes after being stomped on.
4 people were actively using chat, but again for some stupid jokes, comments.
Neither had any idea how to play the game, one even admitted that he just recently started and is learning by doing instead of doing bot games or investing time in online guides, Silver was spending like 1 min per item purchase during the game in base, browsing through I guess whole thing, even when our base was under attack

and didn't see it as a big issue based on chat.
All in all I would say that ranked atm is just "fake" and every game is compiled like pubs = randomly more or less.
Still I would distinguish two cases:
1. game puts intentionally really really good players into the match that are just better brain and aim wise, possible X stacks vs randoms = that is bad matchmaking
2. game puts random people / at most duos in a game where most are just lazy uncompetitive players = they die / feed during lane phase and game spirals out of control fast = that is on community not matchamaking to learn the game first before actually playing it. Most screenshots here seem to fall in this category = some people doing 8-12 kills while others do 0... that is not a bad matchmaking imo.