Its not the same thing. min-content/max-content/fit-content etc for these form control elements are some magical value (for textareas "1lh * attr(rows)") for example. (This works cross browser!)

min-content/etc get invoke in more places than you'd expect. For example:

  <table>
    <tr>
      <td>
        <input style="width: 100%">
      </td>
    </tr>
    <tr>
      <td>
        <input style="width: 100%">
      </td>
    </tr>
  </table>

Here when initially sizing the table the "width:100%" will actually be "width:min-content". (We can't change how this works, it'll break sites, and I'm oversimplifying slightly).

This property is basically a switch to say "don't use the magical values for the intrinsic sizes size based on your content instead".

With the new form-sizing property (or whatever it gets named) all the inputs in that table will be sized to the maximum input.

I understand its frustrating but changing a 20+ year platform isn't an easy/simple affair sometimes :).