It is also possible that the article mistook the cell discharge curve with their self discharge. Self discharge happens due to imperfect chemistry regardless of what is connected to the battery: you charge a cell at 100% then put it in a drawer, and after some time it falls below any usable current by itself. Usually it takes months but I had very poor cells self discharging in less than two weeks, although they could indeed deliver the advertised current in shorter times.

As you pointed out, NiMH cells have a much flatter curve than alkaline ones, but they also self discharge quicker than alkalines, so for example in very low power devices such as remote controls or clocks where one would expect long times between recharges, they aren't the best option because their self discharge time is much shorter than their use time.

In my kitchen I have an exception: an old electromechanical wall clock in which I swapped the alkaline cell with a NiMH one, but both use and self discharge are dealt with by a small solar panel connected in parallel with the cell, which in this case works as a voltage stabilizer too. So far about 4 years passed without changing or recharging anything, and it gets direct sunlight for a very short time every day.