Well what archetypes and decks is it dismantling right now? Give me an example.

Buff decks.

Shackles is fine. It's a worse neutral version of Kaedweni Sergeant.

lol

Kaedweni Sargeant: "Convert a Gold unit to Silver (or Bronze, if that was its original color)." Shackles: "Reset any unit on the battlefield to its base strength. If Gold, convert it to Silver (or Bronze, if that was its original color). "

Its literally the exact opposite what you say.

It doesn't provide strength, cycle, resurrection, nor anything aside from demoting a unit, the card often provides mediocre value.

What does that have to do with its balance? You're right, its not like the other cards, but that doesn't mean its balanced lol.

You can't just nerf cards in a vacuum. Adjustments have to be flexible and made to fit the meta.

No doubt. But that doesn't answer the question. What does popularity have to do with balance? Its a rhetorical question. You shouldn't have even attempted to answer it. Popularity has nothing to do with balance, and suggesting it does, is evidence you aren't versed in the subject. Continuing to argue after you've been proven wrong solidifies that.