No, the lesson is that if you have a service that provides an important social benefit, you account for it and fund it. You don't embark on cutting routes purely as a financial saving.
I also don't get this distinction that a lot of pro-closure beople have between "a Beeching closure" and "a BR led closure". Beeching was a Chairman of BR and set the ethos of the organisation to a considerable extent, therefore a Beeching closure was a BR led closure. The run-down and closure may have taken place after Beeching left, but he instilled the theory behind it.
That line didn't have an "important social benefit" though - it was at best a secondary line, the places it ran through had alternative rail and bus provision - quite extensively so in the case of the buses.
You're doing your usual game of 'buzz word bingo' about any closure. That said I'm surprised you didn't take the bait about it being a far better line as a tram than it every could have been as heavy rail.