> peace of mind of knowing PNG is always lossless

There is pngquant:

> a command-line utility and a library for lossy compression of PNG images.

You also have things like https://tinypng.com which do (basically) lossy PNG for you. Works pretty well.

Neither of these are really what I'm referring to, as I view these as ~equivalent to converting a jpeg to png. What I mean is within a pipeline, once you have ingested a [png|webp|jpeg] and you need to now render it at various sizes or with various filters for $purposes. If you have a png, you know that you should always maintain losslessness. If you have a jpeg, you know you don't. You don't need to inspect the file or store additional metadata, the extension alone tells you what you need to know. But when you have a webp, the default assumption is that it's lossy but it can sometimes be otherwise.

Actually, if you already have loss, you should try as hard as possible to avoid further loss.

I don't disagree, in principle. But if I have a lossy 28MP jpeg, I'm not going to encode it as a lossless thumbnail (or other scaled-down version).