Whenever we add custom site definition using stsadm -o addtemplate command it is recognized as global site definition.
In the article above it points to custom site definition which are installed using stsadm command as they became global in template collection. so article points to feature stappling is possible with custom site definition also.
Process of associating feature with all site creations through all-site definitions is possible by using Global in templatename only. and you can narrow down to specific template by specifying #0,#1..