I believe they are using 'exponential' as a colloquialism rather than a strict mathematical definition.
That aside, we would need to see some evidence of AI developments being bootstrapped by the previous SOTA model as key part of building the next model.
For now, it's still human researchers pushing the SOTA models forwards.
When people use the term exponential I feel that what they really mean is 'making something so _good_ that it can be used to make the N+1 iteration _more good_ than the last.
That aside, we would need to see some evidence of AI developments being bootstrapped by the previous SOTA model as key part of building the next model.
For now, it's still human researchers pushing the SOTA models forwards.
When people use the term exponential I feel that what they really mean is 'making something so _good_ that it can be used to make the N+1 iteration _more good_ than the last.