I'll assume a one-dimensional data table to keep it simple

Suppose cell A1 really is an input and is equal to 3. Suppose cell A2
has a formula in it, that says =2*A1, so it is 2*3 = 6.

Suppose cell A3 has a formula in it that says = 2*A1 + 2*A2. So it is
equal to 2*3 + 2* 6 = 18.

I now create a data table for cell A3 with cell A2 as the input, i.e.,
varied parameter. So, if cell A2 takes on a value of 4, it blindly
will say that cell A3 is equal to 2*3 + 2*4 = 6+8 =4.

But, we know that for cell A2 to be equal to 4, cell A1 would need to
be equal to 2. But it clearly is still equal to 3.

Do you see my point?

Thanks