There are many blog open source soft ware like wordpress, e.g. nuclus, xoops, Movable Type(perl / PHP), MODx, OpenPNE(SNS), etc.,
Almost all of cms application are same structure like PHP, MySQL or Postgres.
Shopping cart application (zend cart, EC-Cube, e-commerce, oscommerce, etc.) are basically design for cart system. And also Shopping cart application structure are same as blog application(PHP, MySQL or Postgres). It means that the installation guid will lead you to shopping cart site easily, no need to find or develop addictional plugins.
Some of blog application have shopping cart plugins, like wardpress. If you well known about application, you can develop cms system as you like Weblog or cart system anyone.
I think this is saturngod Profissional.
The people who know well about php and database structure, they will develop their own site. They don't use cms I think.
but I love both joomla and wordpress too. instead we use plugins to extend wordpress or joomla as a shopping website. I prefer to use open sources such as Presta ,Open Cart ..etc
I'm here not debating on your discussion , this is just sharing my opinion :) thz