If Android manufacturers ship devices with out-of-date software and updates disabled, I don't think there's much we can do about this. It's the same problem as shipping an old version of Chrome with updates disabled, and then finding that certain websites don't work. Obviously if you want to make sure new content works then the software needs to be up-to-date. If you disable updates then you make newer content broken by default. So it's a terrible decision to make it the default.
The C3 runtime requires more modern browser features than the C2 runtime, but it should still work if there is a webview available that has been updated any time in the past 2 years. I am mystified as to how even older webviews could have any kind of prevalence on the market...