Where it really excels IME is as a target format for design authoring tools, most notably After Effects, which is discussed above the fold in the linked article as the original motivation for the library and the file format. No one is writing stuff like that by hand to begin with.
I've worked with Lottie animations as a mobile app dev, but never authored one.
It’s not trivial to produce a Lottie file in After Effects. 95% of the app’s features are off limits, so it’s practically impossible to take an existing AE project and convert it.
Instead you have to ask an artist to author a project from scratch within Lottie’s limitations, but of course there’s no feedback within AE itself if you’re overstepping the boundaries, so they have to be particularly careful.
I wouldn’t recommend it based on my personal experience. But I guess there are teams who have the diligence to make it work.