Is it at all practical to try to use Joomla or Drupal to design anything but brochure-ware or a blogging website? Are the modules/extensions frameworks really flexible enough for designing web applications that have a lot of data entry and reporting capabilities, or would you just be better designing it using a MVC framework, ASP.NET or just plain to-the-metal PHP?
Say you want to design a web application that is primarely used for entering in data and reporting on that data. For example: you want to design a website for people that own race horses.
Primary data entry involves user entering in the physical attributes and race records for all their horses.
Reporting is available for finding statistics and other metrics based on the physical attributes and race records for all the horses in the database: the users and what others have entered.
What would be the reasons or benefits of doing this in a CMS?
I do it all the time with a proprietary CMS. I'm sure it's possible to write any kind of plugin/subsystem for drupal etc.
Benefits:
Drawbacks:
If the CMS is modular/extensible enough that you can write your own extensions without to many restrictions, I would definitely go that route. Think of some 'non core' tasks you would otherwise have to implement yourself:
Working heavily with Drupal recently I can say that it is well suited for stuff like this (except a certain lack concerning database abstraction, since it currently only supports MySQL and PostgreSQL).
You can set up a standard site pretty fast and focus your custom development on your core tasks by creating one or more custom modules that do all the data gathering and reporting tasks you need.
The downside is of course the learning curve - you should think of the CMS as a framework like any other that will take its toll while learning the ins and outs.