If we say about some store site - it is possible.
if we say about sites like amazon - you will need as small 1 - 2 developers in support team
serious site ask:
- serious hosting
- serious support
- serious advertisment
and Joomla as start is very good solution.
Now on OS CCK website Builder
you may create:
- any catalog website (car, book, houses ...)
- any content access website(documents, video, files, content)
- any rent/booking website (car, book, houses ...)
- any shop website(real goods or software)
- any CRM website, but because we think there are will need many Print and PDF reports - we now are adding PDF and Print layouts, sorry this not so simply as we thought
BUT there yet very many what need add...