Looking around the US, parcels with buildings on them have the address tagged onto the building.
Parcels without buildings have an address point somewhere on the parcel.

This seems to be the most logical way to handle addresses.

If there are no objections to this approach, I will start working on the conflation process, as described above.

There is a simillar discussion under one of my other changesets:
https://www.openstreetmap.org/changeset/165860808