That's very definitely not true. Perhaps they're defaulting to Snap for convenience, but Certbot is a cross-platform Python program, and can just be installed via pip: https://certbot.eff.org/instructions?ws=nginx&os=pip

Non-Ubuntu distros also often have standard packages in their repos with no reference to Snap, and EFF also distributes a Docker container with Certbot pre-configured, if Docker is your thing.