I have not noticed any articles claiming that people using e-bikes got a better workout. Lots of comments that people will ride further on an e-bike with less worry about bonking and people that would ride one circuit on trails and with an e-bike would consider doing a second circuit but that cannot be generalized to everyone on an e-bike.
E-bike help with riding up steep hills or riding into a strong headwind. One can also adjust the amount of pedal assistance provided by the motor for the situation and the fitness of the rider.
Not all that different from when triple chainrings started to appear and bikes had incredibly low gears more suited to pulling a cargo trailer.