There needs to be a Linux kernel fork that when you try to execute a directory executes all programs in the directory. In parallel. Juuuuuuuust to fuck with people who might accidentally execute the /usr/bin directory.

For directories, it’s permission to cd into it. Read is whether you can list files, and write is remove, rename, or create new files. Don’t ask questions about the secret sticky bit

The x permission on directories is exactly for this purpose. You can use the directory. You cannot read (requires rx), you cannot write (w), but you can 'cd' and operate on files in the directory.

This is important, you can lock someone out from a directory tree buy not giving them 'x' on the root. So, if your home is rwx------, no one but the owner can do anything in your home. This is effective even if some files and subdirectories have less restrictive permissions.

Executing a list read of the inode?

It's necessary if you want to give somebody rw access to a subdirectory but not the parent.

The parent gets "x" and the child gets "rwx".

This way you can have multiple users with their own directories under, say, /var/www/html but restrict access to /var/www/html itself.

If the user doesn't have "x" then they can't see anything in that directory at all.