No, i mean, what's wrong with having a webui? Digitalocean, Linode, Vultr, Upcloud, nothing requires you to have something installed. Why is Fly io different?
i don't work for fly so i'm not exactly an authority but as someone with quite a bit of cli experience i can get something done 50x quicker than with a webui. there's added bonuses too, you can use cli programs in ci build tasks.