> or host anything itself.

It does, or there would be nothing to download.

> and the system processes them on demand > Webtor is a tool, not a content provider

By assembling the chunks into content it then provides via a link to download.

Is the implication here that the data is transient (eg time-gated or single use links) or something?

We're in the age of AI and Automation. Just because you aren't publishing an index of your content doesn't mean there aren't plenty of others searching, indexing, scraping, and aggregating it, nor does it mean the content isn't provided to the internet/public.