Who wants to own something and have another thing you have to worry about and take everywhere with you? When you can just join an app, have no up front cost and dump it on the street for the next person? That factor of convenience beats the shit out of ownership.
Regarding handling - do you think someone with no experience riding a bike can 'effortlessly ride 10 miles on convoluted paths without touching the handlebars' or did it take you years of riding experience to get that good? So if you spent that same amount of time riding an e-scooter do you think you'd have handling down to an art as well? I think you would, and how it handles around corners wouldn't even be a consideration.
However theres a halo effect at play here which is good news: more people who are using these services who have never used an e-bike or boosted board before after seeing the benefits are now more likely to owning them. Or maybe even just buying their own Xiamoi E-scooter.
The exercise benefits of both are... questionable. Even just cycling as a commuter on a regular bike isn't very intense exercise, and on an ebike it just seems like you're pretending to pedal. I can't imagine it has much health benefit aside from being better than sitting in a car.