Someone mentioned that client want to use wordpress instead of they current website because it is cheaper! Ok lets see how cheap it is.. each time wp release update after updating you need go through all website and check if nothing is broken.. plugins will need update as well because usually they run on specific wp version. Fixing theme and plugins requires dev time.. despite all those things.. have common sense. Maybe it is good for some type of business to host few pages without any business logic or use as blog without scare to loose everything and do not store users data.. someone mentioned that it is secure to run anything because updates are the best security to avoid security breaches. So why banks are not running on WP? Why health service is not using WP?