I'm with Josh on this one.
Dimensions shown to existing buildings from the lot line is common on many site surveys, and A.L.T.A.s.
Showing the same dimensions to a proposed building is also common, and not 'illegal'. The true issue here would be the accuracy, or better the precision of those dimensions. So if the survey or cadd technician doesn't use proper care to insure that the dimensions are placed perpendicular to the calculated lot line (not assumed); and those dimensions are true therein lies the potential legal problem of encroaching on either A)setback lines, or B) adjacent property owners parcels comes into play. I have worked with individuals in the past who did not understand that the survey drawing is in fact a legal instrument and all dimensions and measurements shown must be as accurate and as precise as is practicable. It would almost suggest that failing to place the building dimensions relative to a calculated lot line, would be the negligent act, not the inclusion of same. Given that B) the lot lines were properly surveyed and adjusted, and B) the dimensions were correct.
From ALTA requirements:
http://www.trgpsc.com/download/ALTASurveyReq.pdf6. Identify, and show or note, the Zoning Classification and the name of that district, the
permitted uses, setback, height, bulk, density and parking restrictions of record or
disclosed by applicable zoning or building codes (in addition to those recorded in
subdivision maps). Also list the source of your information, that is, to whom you talked
to at the zoning authority, their title, address and phone number. It is understood that the
surveyor will state information and facts of record and will show all plot able items on
the survey.
And while not specifically called out; how else would the surveyor note the facts of record as stated above without showing a few dimensions to tie the building to the site lines, and easements as required in #6 above?