I find it bizarre that GIFs are even still around. Haven't they been replaced by two better standards at this point? Then 10 years ago someone dragged them out of the bin like a stack of old vinyls and they've hung around like a bad smell ever since.
"GIF", at this point, is more of a placeholder name. For GIPHY in particular, the API will give you a GIF if you really want that, but also various other formats:
The GIPHY Developer Portal is how you integrate the world's best GIF API into your business, app or project.
developers.giphy.com
So when people say they are posting a GIF, it's more in the figurative sense of an animated image without sound; others may actually see it as MP4/H.264 or WebP/VP9.
The real value of the purchase is not the tool. It is
1. The user data, the eyeballs and the penetration of it into a bunch of platforms (slack, google, apple..)
2. The tracking data which is embedded into each one of the GIFs that exist in the platform.
So from now on, each time you post a giphy, FB will know where, when, the exact words you were looking for and your mood at that moment.