I used Plato as an example of this because the first example that came to mind was classical philosophy, or at least the parts of it that aren't more properly philology.

I'm generalizing over my experiences at philosophy conferences, mainly in the Midwestern United States, and my reading of various philosophical journals. I'm basing my claim on, among other things, what seems to be the common practice of classifying some philosophers as for example "Kant scholars", "Continentals", etc. It's possible I'm wrong. I'm not a professional philosopher. I still think many philosophers think this way. That's where I get this perception.