Is it a good 2048 board?

Haskell, 21 bytes

all$scanr1 max>>=(==)

Try it online!

Takes a list of columns, with empty spaces as 0.

€{íQ

Try it online!

Same as my other two answers. I promise this is my last one until others have answered :)

Takes 4-by-4 matrix, using 0 for blanks, as argument.

⊢≡⌊⍀

Try it online!

⌊⍀ is the vertical cumulative minimum

≡ identical to

⊢ the unmodified argument?