Currently "plat" hovering at around 59-60% winrate..
As a support main I agree that silver is the hardest rank. In Silver you have to "carry harder" and can't relay on your team like you can in higher elo. Get your adc to 10/0 in silver and they find a way to throw it by running around solo in the other teams jungle, and they do it over and over soon they are 10/10. There is rarely any teamplay and everyone is just doing random stuff to throw any lead you give them.
It's also harder to support silvers as they tend to have no understanding of laning. So you end up overpushed and in positions you know are bad again and again, but there is little you can do other than to roll with it. Silvers also struggle hard vs assassins like katarina, regnar or even master yi and tends to die a lot to them. You basically have to be the one to shut down such players on your own in silver.
Also the stuff about silver being smurf land is true as well, in silver there are just so many "high elo" smurfs temporary ranking up new accounts. These smurfs often get massively snowballed in silver. What often happens in silver games is it becomes a "battle of the smurfs", like "we have two diamond smurf" their team has "2 plat and a masters". Then the smurfs decide the game and the true silvers just get carried or stomped depending on who has better smurfs.