People often want to share their seeds so that players can play the same game they did. If there was an interesting series of results for example, which gave you a good set of cards.

Minecraft does this too with world generation for example.

It's a big thing for competition. In a procedural game there's a lot of variation between seeds so the only 'fair' way is to start with the same seed.

(Generally, when you just press 'start game', you'll get a truly random seed, but then you can also put that seed in again to get the same RNG).

Being able to share and replay seeds is a big part of the StS community.