I for one believe he will eventually prove to be a very good OC. However, it's all based on potential. How long do we want to continue to wait for that potential to become reality? I had pretty high hopes for him in '23 but, that was far from a guarantee.
You certainly can't make the case right now that Rees leaving is a definite loss. With what we have coming back on offense there are many viable candidates who can improve the offense. Even just elevating Parker is probably at minimum a push.
Remember all of Rees's failings this year. Especially ones like the 2nd half of Navy. Rees had several questionable performances and they weren't all due to limitations at QB.