Sure, I can have for example my computer be send only. But unless everyone else configures it properly as receive only, they can start pushing data to other clients. It would be far easier to have Syncthing create a readonly share similar to Librevault and Resilio.
I have considered it. The one thing about Syncthing is that there is no true readonly way to sync. For example, someone may accidentally extract an archive in the Syncthing folder and it will sync everywhere. If Syncthing gets this feature I think I would be 100% onboard with it for LAN parties.
Resilio I believe supports it but I would prefer an opensource alternative.
I am working on a tool that will help with this. It is built with AlpineJS, Nim, Aria2 and Webview resulting in a 5MB download which doesn't include the torrent file as that varies. The idea is that it is a one click solution as the torrent is embedded with the binary.
The inspiration for this tool is for assist with LAN parties. The one thing I have against the private flag is that it also disables LAN peer discovery, which would be okay if you use a tracker behind the LAN (though the torrent would need to be modified if the hostname/IP changes). Since you can't configure other people's clients I found it simpler to use Aria2 that is preconfigured to disable PEX and DHT.
Combine this with Metalink or Web Seeds, so that you can have a initial seeder based on HTTP. I think using IPFS would be a great web seed as long as the their gateway and Cloudfare's continues to stay up. IPFS creates a permanent URL if you will, so no need to worry about dynamic IPs or domains. It would be great if IPFS would have a smaller binary (right now it is around 20MB compressed) and had a way to get a file and "seed" it like a torrent. But for now I think torrent is mature enough.
Currently implemented in Nim.
https://gitlab.com/jivank/sambalshare/-/tree/prologue-switch