[killerstorm]

We can reason about it without knowing the path. E.g. somebody in 1950s could say "If you have enough compute you can do photorealistic quality computer graphics". If you ask them how to build a GPU they won't know. Their statement is about principal possibility.

[advael]

Yes, and there are lots of predictions about when that would happen that turned out to be very wrong. Even if there is a clear path and specific people assigned to do a thing, it is famously always more difficult than expected for those people to correctly estimate how long it will take. Forgive me for being skeptical of random laypeople giving me timelines for an unknown unknown based on an objective that is ill-specified for work being done on something for which there is currently a lot of marketing hype