Did Keystones actually add anything to the game?

I'll try to convey my thoughts into words as best as possible.

So, essentially I feel like keystones didn't actually add any sustenance to the game. I feel like all they added was burst and more cheese. For example, I'll use wind seekers blessing. Windseekers pushed many heal/shield supports over the edge. So lets say there was perfect balance before keystones were released and then windseekers was released and soraka suddenly went from a balanced champion to an op one. So riots like with windseekers sorakas getting 10% more heals and now heals to much, so we are going to nerf her heals by 10% thus making the whole point in the keystone just to bring her back to her former glory.

Or Syndra lets say she was balanced before thunder lords, then thunderlords made her too bursty so Riot had to nerf her abilities. now if syndra takes a different mastery she doesn't do enough damage to be useful.

TL/DR: I feel like keystones are actually super empty. I feel like they just made the game unbalanced and then Riot has slowly nerfed champions into being balanced around keystones.

this is a discussion, so lets discuss.

Sorry for how jumbled my speech is.