

Historically, non-animated .gif had some uses. For example small border insets in webpages, when the limited (or non-existant) CSS wasn’t enough.
JPEG is awful at straight corners and lines, basically anything that isn’t a photo. PNG didn’t exist back then.










PNG took forever to reach baseline usability. Obviously because of IE. I don’t remember exactly, but if you targeted IE you couldn’t use a lot of CSS features and PNG support was shaky at best. I think transparency in PNG just didn’t work.