To say the beautiful is strict, absolute, universal, objective, rooted in nature... is only half of the equation. The beautiful is also surprising, original, unaccountable, challenging, recalcitrant, sometimes awful, terrible, tremendous.
The beautiful is a balance between creative power & the inherent proportions of nature. A proportion of proportions.
Even the poems that reject or deny harmony can't escape its presence, lurking in the background.
It's easy to define the beautiful. Much harder to find & defend it. That's the critic's job : to apprehend beauty where it wasn't noticed before.