Agreed.
A first-order approximation leaves a lot to be desired, but it's better than a zeroth-order approximation.
A first-order approximation leaves a lot to be desired, but it's better than a zeroth-order approximation.
If you're coming up to the end of a logistic ("S") curve, then assuming a linear growth (or worse, a fixed rate of increase each year, ie exponential growth) is much worse of an assumption than assuming zero change, if you extrapolate too far.
On the other hand, if you are not interested in making long run predictions but only short run predictions, then first order approximations will tend to be more accurate in a small region around the base, but that region might be quite small.