Too precise I think - you can have multiple GPS coordinates for one address e.g. 2.00000000001 and 2.00000000002 could both be on the same building. Even a bounding box is too error prone.

Also, verticality would be an issue.

That's what they do for car navigation, but they use a proprietary system called Mapcodes instead of just GPS. Some sat-navs there won't even let you input GPS coordinates and you have to convert them to this first.