Elo Hell - The reality.
The answer is there is and isn't elo hell.
There is no such thing as elo hell on paper. Statistically if you play better than your peers, you will climb above them. This is fact.
The type of losses that stem from an elo hell scenario being 'my team is holding me back' would be throwing the game at baron because 4 people decided to do it, and you join in for the sake of doing it faster. You knew the baron was a bad call, but your team did it anyway. You wiped and lost because they were bad and you were good.
Some of us learn by observing so another reality of Elo Hell is smurfing and getting worse by picking up bad habit. You can be stuck in 'elo hell' because all you observe is bad play. Try to watch streams if this is the case.
Lastly -- you have to win differently at certain elos. Unless you can overpower the enemy in a 1 v 5 one man army scenario if you're playing in let's say bronze 4 and you're roughly plat 3 and above, then you might need to employ cheesy tactics. Silver is very bad at closing games out so hard engage champions such as amumu and ping spamming is probably my recommendation.
If you need some advice on the specific methods I recommend winning with in each division here they are. The zz rot one is extra cheesy but it's very effective in specifically gold and probably silver too, but I won't list it there because no one will buy ZZ rots in that elo.
How to win/not lose in every elo, as if you belonged in that elo.
Bronze: Hard engage// also probably assassins if you can play one correctly // Split push if done correctly.
Silver: Hard engage // still probably assassins if you can play one correctly
Gold: Catch and artillery mages like Lux and Xerath can carry really well here due to how teams figured out how to siege properly at this point // Hard engage // catches in general are super important // ZZ rot spam can draw games out and force mistakes if you need a miracle
Plat: same as gold but work on mechanics // know that if you specifically get caught it'll cost you a lot // wait for throws
Diamond: If you get caught the game is basically over // focus on playing carefully // practice mechanics //smart engages while behind can make up for differences as people will rarely throw in this tier so you might as well try to catch up somehow