Not being able to transfer more than 100MB is just them lacking motivation. They don’t even need to host files just make everything bigger than 100 MB a torrent or something similarly p2p. Skype’s file transfers worked like that if I remember right.
Let everyone who wants the file also serve the file to other people that want it.
To be fair P2P file transfer is not always viable, and in some sense the situation may be getting worse as more people are behind NAT these days, and the adoption of IPv6 has been poor. This may not be the end of the world for torrents as long as some peers can be connected to, but private transfers between two people on restricted NATs might not be feasible without Discord acting as a middleman for the transfer (which could get expensive). Plus there are some small privacy concerns for a direct P2P file transfer, as it would leak your IP to anybody you’re transferring a file to… probably not a big deal in most cases, but it might be unexpected for some people. That said it might work fine in many cases when NAT isn’t an issue or when NAT punching works… But there’s also other downsides in terms of reliability, offline delivery, and handling multiple devices and stuff that might make the experience a little less consistent for people.
Nowadays routers are made to be friendly to hole-punching, so, actually, P2P works quite well
