What exactly is the issue with that? Does it matter if the average railway enthusiast/modeller only knows a few engines?
When you first got into the hobby, and many of us, I bet you didn’t know all the different variants of a J39 either. I don’t see why that discredits or renders ‘entry level’ enthusiasts as irrelevant. Sam has a particular audience, and he’s more than entitled to produce content for that audience.
Again, i’ll reiterate, the majority of ‘train people’ are likely more casual. This is not an issue, and to argue otherwise is sheer arrogance.