Excellent observation. The single-threaded effort dominating AI today (i.e. the base assumption that OpenAI can scale GPT up as it is today into AGI) is what's causing the bottleneck.
Assuming AGI can be built as 1 system is assuming that mind is separate from body, which is the old dualist idea we've outgrown in our own awareness, but somehow not when it comes to AI. We've been growing AI in that direction at https://www.aolabs.ai/