its called chaining cc and its a healthy game mechanic. Your argument is basicaly " i got cc'd for a long time so disable the champs kit riot."
Leona can lock people down for that long on her own. she can snare you stun you stun you again, all while her abilities give a damage bonus to your team. And theyre buffing her. She doesnt do much damage so its balanced.
It sounds like you had a rough game, dont know what qss is, and are crying about healthy combos.
A more fun combo is when a team combo is
top malph
jg amumu
mid yasuo
support ali/leona/braum/morg/janna
adc doesnt matter
If amumu ults even half your team, its a free ult on your carries for malphite followed by yasuo's ultimate on your carries, then the support still having enough cc to peel for his when they only have their tanks/bruisers left and you just proceed to clean up.