How "Noun + Adj + Adj + 的" (reduplication of adjectives) is grammatically equivalent to "Noun + (Adv of degree) + Adj"?
How “Noun + Adj + Adj + 的” (reduplication of adjectives) is grammatically equivalent to “Noun + (Adv of degree) + Adj”?

[Noun + Adj X2 + 的] = [Noun + degree adv + adj]

Both are 'topic-comment' sentence

[Adj X2 + 的] functions the same as [degree adv + adj] in this case (a noun at the beginning but no noun at the end)