I don't think largeness is the problem. It's language design. C++ is just really badly designed. I'd be very happy with a very large language that takes a long time to get familiar, if all the features in the language are well designed. IMO the current developer landscape is all about "fast onboarding", but that is the totally wrong metric to optimize for. To me it's the difference between someone walking and an airplane. Sure it's very easy to just start walking, you ain't going to go anywhere fast. On the other hand an airplane takes orders of magnitude longer to get going but once it does you won't ever catch up to it by walking.
I think this is a good point. If you learn a language and it's useful, you usually use it for many, many years. So long as the daily driving experience is great, onboarding doesn't have to be that important of a metric.