And lots of single points of failure, literally as it were .... a few years back there was such a service and I think there was a period during which it had to reverse at Gresty Lane or somewhere similar because of a points failure on the normal route from platform 6 to Manchester.
The Chester-Crewe-Airport service was introduced by NWT in about 2000 as compensation for cancelling their plans at privatisation for through services from Chester/North Wales to Euston.
For several months after launch they could not reach P6 at Crewe from Chester because the diamond crossing was out of use, so used P11 and then set off south towards Shrewsbury and reversed at Gresty Lane to come back through Crewe to take the Manchester route.
The service didn't survive the cutbacks during WCRM and ATW did not bring it back.
Always a Pacer and waited outside the Airport for ages for a platform.
I suspect North Wales- Manchester is a much smaller market than Chester- Manchester . The latter has alternative direct services and political clout from the Welsh Govt is irrelevant if it gets in the way of relieving Castlefield. I fail to see why "via Northwich" is an issue if the associated problems can be solved because any direct service is better than a connection
Chester/North Wales is no smaller a market than Lancaster/Cumbria, and has much the same tourist pull, yet no-one tries to cut Cumbria's links to Manchester and the Airport.
The WG does have clout in the debate, and can't just be elbowed aside by DfT and Andy Burnham.
The TfW TOC has as much right to Castlefield as, say, EMR with 1tph.
If the only practical solution is via Northwich, there would need to be infrastructure improvements to obtain a competitive journey time to the Warrington route.
It wouldn't have been an issue if the Airport station had been linked to the CLC at Mobberley.