The point of that is that renting confers specific benefits that make it worthwhile despite the downsides. First off, no need to charge. Not the worst thing but there's nothing worse than running out of battery because you forgot to charge it. Additionally, no maintenance - the company employs mechanics that are better positioned to fix the scooters. Finally, no need to have the scooter with you - just use it whenever you want, in one direction, and then not have to lug a scooter with you for the rest of the day. Or, if you didn't ride it in, you can't use it for the rest of the day. If it's raining in the morning but clear in the evening, you don't have the scooter to ride home unless you rode it in for your morning commute.

Now, you may not find that list enough to offset the downsides compared to buying your own, but judging from their seeming success, I'm not the only person that's done the math and intentionally chooses renting a scooter as-needed.