Given that Starlink will probably solve the same set of problems within a few years (that being access to internet worldwide in areas with minimal infrastructure) this isn't too much of a surprise to me.
You connect to Loon balloons with your regular cellphone whereas StarLink requires a "pizza-box-sized" antenna. They solve slightly different problems.
It's likely easier to set up a solar powered cell tower on the ground with a starlink antenna on top, than to float the same equipment on a balloon though.
That's a 12 inch medium pizza, without the box. An antenna of that size can't be carried by normal people going about their daily lives.
More people are willing to buy a phone and a phone plan (Facebook was even willing to subsidize the plan in India with Internet.org) than buying a phone, a phone plan, an antenna and a StarLink plan. That's even more true for people who aren't internet users yet.
Most people will already have a phone and a phone plan but missing coverage in many places. Starlink makes it pretty cheap and easy for network operators to place solar/wind powered cell towers without need to dig wired connections or make microwave chains. That can seriously speed up the rollout to improve coverage. And users don't have to do anything.
