It seems appraisals are held to a lower standard in context of what is credible results for a 2055, ( see the certs and disclaimers ) An appraiser can not be held to a standard they can not meet, and if appraiser not allowed access/not expected to measure on a 2055 or desktop, then a client /intended user recognizes sf being "off" is more of a possibility, despite appraiser's efforts to verify/discover.
The standard is lower but the expectation on client side is also lower for a 2055/desktop, - why they have not been typically used in origination work - the path is being paved for that to change it appears