"The real play is when you've got small networks of co-workers or friends who can share whatever they want securely," Rogers said in an interview. "It could be a group of government officials sharing secure documents or it could be Justin sharing video files with AOL Dulles."
IMHO (yours may differ) much of what we use the internet for, namely person-to-person or person-to-small-group communication, could be accomplished using such software, as an alternative but not a replacement for doing these tasks over someone else's website. Those websites have grown to such ridiculous size, backed by entire datacenters, that people refer to them as "services" and "platforms". But for the task of communicating over the internet, as the programmer saying goes, "There's more than one way to do it." With the gigantic websites run by other people, there's an incentive for advertising. Large audiences and easy access to them, not to mention the ability to eavesdrop and track behaviour. With small networks managed only by the participants using software they choose, that incentive does not exist because advertising is relatively infeasible. For example, the top commenter in this thread states he has been running a WASTE network for years. How does one inject advertising and track consumer behaviour on his network. The answer is they don't. And IMHO that's one reason why this category of software is so useful.
File Transfer: https://xkcd.com/949/
This is still an issue in 2023. Dropbox and Google Drive aren't new, and ironically Megaupload is now a Dropbox/Drive competitor Mega + Rapidshare is long dead. But emailing files or physically sharing on a USB drive is still the best way to share files ad-hoc. Dropbox etc does work, but you have to make a new account and mess around with settings and permissions.
Because its remaining an issue enables "value extraction". Magic wormhole would work if people knew about it but somehow software that promotes itself by honest word-of-mouth has difficulty competing with software that is bundled with Windows or is made by the world's largest advertising corporation.