Quote:So if you have an optimized and compressed JPG that appears "good", no reason to use webp
Not necessarily, There will be situations where you need to squeeze a bit out of the file size for posting on a web site. Jpeg compression is not linear, values 60 and below, plenty loss in quality for not much reduction in file size.
PNG format: png image = 195 KB Lossless (for equivalence) webp = 175 KB a 10 % saving but with 90 compression the webp = 71 KB
As the old saying goes, You pays your money, You makes your choice Up to you to decide on format depending on circumstance.
Video is more dramatic.
48 frames pulled out of a video - a cartoon, small frame 320x218 suitable for animations, as 48 individual jpegs of not great quality.
exported as an optimized gif animation, size 843 KB
exported as a 50 quality webp animation size, 160 KB an 80% saving in size and you keep all the colours.