The problem really boils down to WebP having no purpose to exist for any user, therefore no reason to waste time and introduce vulnerabilities for its support, especially for feature-complete software. An image format (actually not, one of those video keyframes formats that have little to do with images, let alone photos, and in its case it's 2-in-1 too with lossless), that was already outperformed by mozjpeg on its initial release as far as human eyes are concerned, and thoroughly obsoleted by jpegli..