> cannot be used to infer any sort of near-time
It's not meant to, it's meant to dispel the common notion that no progress is being made in this area of research.
And the total power output doesn't need to remain exponential for fusion to be viable, we just need a way to sustain fusion reactions for a long enough period of time (china recently set a record with 101 seconds).
Seriously look into all the work being done on this currently by Government projects and private companies. I'm not saying it'll happen soon but significant progress has indeed been happening for a long time, and is only picking up pace as time goes on. As I said, this is likely the most difficult thing humans have ever attempted.