If you mean why a desktop app: I've been using some web-based tools. Somehow, they don't last (ie. namemesh, or domainsfortherestofus that @pwdisswordfish8 mention went offline for sometimes).
Then I thought having a desktop app would be great. For long term, you don't have to worry the site is down.
Cmon man, let’s try to be realistic.
If GH pages goes down, you wait for it to come back. The point is that GH pages won’t disappear because of passage of time (ie you forget to pay hosting bill or something). It doesn’t guarantee 100% uptime but it doesn’t have to. The desktop download doesn’t guarantee 100% availability either.
If the tool is that critical to your workflow, you save it offline or host it on a redundant location (there are many free static site hosting services available: cloudflare worker sites, digitalocean apps, S3 — take your pick, maybe one has the uptime guarantees you desire, GH was just an example. Or host it in multiple)