Every year, I read posts from real plat and diamond players smurfing in silver and saying there are games they legitimately cannot carry - and they're not stuck on support in those games either.
In the past, one exceptional player could out-shine one really bad one, but this season especially, that is generally untrue unless you main adc and are god tier in low elo.
Like your jungler deciding to suicide to your laner 2x, gift them doubles, and steal all cs to freeze for your opponent every time you base so that despite missing maybe 5 cs by lvl 4, your opponent is now level 6 through literally 0 fault of your own. And... bot is losing gracefully and mid is getting bodied. And your jungler is 3 levels behind the enemy jg despite stealing 40 cs from you. Yep, if you were good, you would totally carry that. End highest farm on your team w/o stealing from teammates and 4/2/0 kda thanks to good roams and tp plays to help bot lane and mid. But it's still an ff @ 15 rather than play another 2 and watch nexus implode. Totally carryable if you were just... a mid tier gold stuck in mid tier silver or something like that.
Last season I legit had a 90% loss rate for 2 weeks in a row because I would get 1-2 lanes that go 1/7/0 and half the farm of their opponent, unwilling to adjust play, unwilling to show any attempt at teamwork. I dropped from s3 to s5 0lp. Then I got reasonable matches with teammates who generally performed on-par with their opponents and would work with each other to make INTELLIGENT plays. They didn't always win lane and sometimes lost pretty badly - on a rare blue moon my team could carry me even if I'd chosen to run it down lane (didn't but could have). But aside from those few rare occasions, my teammates were not hard carrying games, yet in less than 2 weeks, I climbed from s5 0lp to g5. I continued climbing to g3. Now I didn't magically get massively better while dropping from s3 to s5, so the difference is purely that my teams went from literally impossible to carry to... reasonable. And this is a previous season gold player... who was stuck in bot tiers of silver for those 2 weeks unable to buy a win even if he goes 4/0/0 while being camped by enemy jungle for 20 minutes and being able to 1v2 anyone on the other team. There are games completely uncarryable. And even if you deserve much higher rank than you currently are, it can take a TON of perseverance to achieve that rank.