The point of Lottie is not simple animations like CSS transitions, but complex arbitrary animations, more like a cartoon than a minor piece of motion.
A good example is the Telegram messenger that uses Lottie as the format of animated stickers, e.g. https://tlgrm.eu/stickers/Princess (click to animate).
Yes, and I think Lottie is very fitting for that use case! I was referring to reaching for Lottie even for simple small animations, because it seems easier to just drop the designer’s Lottie file into the project, rather than building the animation in a more native way. At least I’ve witnessed recommendations like this on Reddit.
Oh, I think I see your meaning. Sure, for trivial translation and rotation, even scaling, I wouldn't expect or want to take a new dependency on the library. But if I already have Lottie in the bundle and a completed example of the animation in Lottie format, how much sense in the general case does it make to reimplement instead of using what I have? It will take pixel peeping and I would most likely do better to spend the same time on something a designer can't also do.
Amazing how many of those are using it to animate unrealistic, exaggerated boob physics