Bill, That is not entirely true.
Stock certificates are individually and distinctively marked.
They indicate the certificate number, number of share held, class, voting rights and so forth. When issues arise as to proper registration such as conflict in name between account and certificates or 144 restricted stocks, the stock or certificate cannot be sold until the issue is resolved. I know this from experience from clients in the past trying to assign 144 restricted certificates or certificates that were registered differently than the registration on the account. In each instance, the assignment was stopped as a result of confirmation with the transfer agent. There is no risk of fraud if the transfer agent does what it is supposed to do.