I'm pretty sure that even when we don't know how accurately it can measure the 'absolute' values, we can clearly see the change which is relative to the comment

I'm pretty sure that even when we don't know how accurately it can measure the 'absolute' values, we can clearly see the change which is relative to the comments on the same context and domain. It can be argued if it really measures happiness etc., but I'm sure there's correlation in the change even if it's not accurate.