I think because Syncthing isn't really for "sharing" files. It can move large files across the internet but it's not designed for "hey send me a copy of that blu-ray your ripped" sharing.
If your swiss, just use swisstransfer.com. it's fast, supports up to 50gb of data, 500 transfers per day (and free!), more than you'll ever need. Although for security, they do say your filles are sent over https, but because they do not promote encryption I suppose they don't support that (although they do support password protected files).
So yeah, it's usually more than enough for most use cases, although I'd encrypt my files before sending them if they contain sensitive data, but that's rarely the case.
