Whys Cassiopiea and Singes win rates so high?

I couldn't help but notice that cass's win rate is staggeringly high currently at 55% on op.gg but it makes me question what in particular is causing this and I think I might have an idea on why.

Most champions in the current meta rely immensely on a dash/blink based mechanic to either engage on their opponents or disengage from team fights (khazix e, Kayn's q and ultimate, rek'sai's ultimate, Warwick q and ultimate and so forth.) but despite them having these abilities that would normally reward them with a kill or a great engage in a team fight, they are severally hindered by champions like cassiopiea and singed's abilities to prevent that. unlike most champions singe and cassiopiea have a unique grounding snare in their kits (miasma for cass and mega adhesive for singe) on the surface it seems like a simple cc move but honestly provides too much in both team fights and solo killing.

Grounded strength and solo laning:

In a solo fight the grounding abilities provides a lot of zoning potential and pressure that a jungle can take advantage of but besides it being a escape prevention it is a also a massive reversal tool. For this example think of a champion who relies heavily on dash based abilities such as kayn or riven. when fighting champions like singe or cass who have these exceedingly long grounding abilities, you'll find yourself unable to ever gap close and finish them off. If placed in a scenario where you've shaved them down low enough to kill and want to go in to punish them for over extending, even though they are low should have been punished for going into your range a well placed miasma or adhesive easily locks up your entire kit making you unable to flash in or away from the enemy and because the slow on these abilities is so strong it gives them time to get so much free damage and a potential kill on you for what should have been you punishing them for over extending but even more difficult is the movement speed buff they gain during this which makes catching them by default extremely challenging and allows them to snow ball the game in their favor (in singes case what makes him so strong is his ability to just run with the late game no matter how well you dealt with him early.)

Team fights:

In team fights who ever can pick out an enemy with as little casualties as possible wins the game and both do a exceedingly good job at that. If your team is hit by a miasma it is basically a massive suppress on a your team which means the enemy team will be able to unload their kits on your team and because your all locked out from vital sums and abilities your chances of fighting back become close to impossible. If each person on your team loses 1 ability and sum that means that their team not only gains 5 extra abilities on you but your team loses more then 4k-9k worth of damage that could have been used on the enemy and because most characters only last for a second in late game team fights its basically gg.

Thoughts?: So anyone got an opinion on this matter cause I personally feel this portion of their kits is simply too strong with very little counterplay and given their high play rates and wins might need to be tweaked.