Services like the 71 are mainly about maintaining some level of public transport for the places that are not in the main inter-urban network, or providing secondary links across the grain of primary services. While services like these are never going to pull up trees in terms of changing the behaviour of car drivers, they definitely have a role.
An hourly frequency is obviously a limitation, but there are situations where an hourly service is all that can be justified by loadings or afforded in anything like the current real world. They work better in a world of better-priced zonal tickets - pricing of the Co Dirham iticket s still  ok, but the lack of a similarly priced bus to bus zonal ticket for travel in/into Tyne and Wear is regrettable.
A link with 725 would help anyone travelling between west Chester le Street and Fencehouses/Houghton etc, though there are not likely to be all that many so only a minor effect on viability.  But it would be an operational benefit - while the 71 cycle is unstressed, the 725 cycle has only short dwells and it must be difficult to recover any delays.