This kind of answer are not good for the long term usefulness of the site for the same reason that link only answers are frowned upon. In the future, the chances are good that users will eventually move away from the site, get rid of assets or change contact information.
This results in the accumulation of large numbers of answers that could potentially have no benefit and puts an immense burden on someone looking for an answer to filter through answers that may no longer be valid, but can only be tested through a time consuming process of contacting each answerer directly.
How do we want to handle this type of answer going forward and do we want to do any clean up of these kinds of answers that are historically present on the site?