Why would anybody care about the format that Facebook users use? I see way more value in reencoding company website images in WebP so that things load faster at the same quality. This is especially useful if your visitors are fairly technical, i.e. when you are a systems software vendor or when you're a tech blogger: even if WebP is only supported by Chrome and Firefox, it means half of your audience can enjoy the faster loading times. With HTTP content negotiation you can gracefully fallback to JPG. WebP does not need the support of Facebook users to become valuable.