Yes that would be great but there are ways around, which sometimes give even better results.
Copied from my answer in another thread.
Locking Cells in Numbers - Apple Community
Put a formatting table behind the main one where cell formulas give exactly the results that you need for the conditional formatting, and you format that cell. You can even put an infinite number of tables on top of each other to get formatting based on various conditions.
Example: Content of 'Table 1'::A1 is irrelevant, but you want to conditionally format it if the value of B1 + 3 * C1 is larger than the value of D1. 'Table 1 - Format' placed just behind comes to the rescue. In cell 'Table 1 - Format'::A1 you enter formula
'Table 1'::B1+3*'Table 1'::C1>'Table 1'::D1
which gives a TRUE or FALSE result, and you format that cell accordingly. Numerical or text results are fine too, of course. Just make sure conditional formatting gives cell background and font the same color to avoid obstruction with front cell content.
The possibilities are endless and if you only want to identically colorize a small set of cells you can actually create a formatting table smaller than the main table and locate it judiciously. In a 20 x 20 table you may want to only conditionally format block B5:C8 based on a unique complex condition. Nothing stops you from putting behind a 1 x 1 table with a single extra big cell as big as the block of 8 cells in front.