Practically, to verify any downloaded or received content or data or email or file's authenticity, a user need to verify their downloaded main content or main data/email or main file's PGP/GPG signature code/file (ASC, SIG). So users would need to use original developer's or original author's trustworthy and verified public-key, or users would need to use trustworthy file-signing public-key trusted-by the original owner of that public-key. And to really trust a specific PGP/GPG key, users would need to physically meet with very specific original author or developer, or users would need to physically meet with the original-releaser of file-signing pub-key, or, users would need to find another alternative trustworthy user, who is in trusted-chain of WOT (aka, another user or another developer or another author, who is trusted by that very specific original author or developer), and then physically meet with that person, to verify their real ID with his/her PGP/GPG key (and also provide your own ID and key to the other user, so that both side can sign/certify and trust each other's PGP/GPG key). Whether a software is popular or not, software users are usually located around the world in different locations. It is physically not possible for an original author or developer or file-releaser to provide public-key or trust or ID verification services to millions of users. Neither is it practical for millions of software users to physically meet with each and every software or every software-library or every piece of code's developer or author or releaser, which they will (use or) need to use in their computers. Even with multiple trusted people/person (by original-author) in trusted-chain from WOT, its still not physically or practically possible for every developer or author to meet with every other users, and it is also not possible for every users to meet with hundreds of developers whose software they will be using or working on. When this decentralized hierarchy based WoT chain model will become popular and used by most nearby users, only then physical meeting and pub-key certify and sign procedure of WoT will be easier.