it is the nature of the kinds of web tool that we mostly use them. they are typically in similar in a fashion that we add tamplets to change way of how the plugins look.for example, world press, you can add features by adding a plugins.
if you need sliders in your blog, so use plugin directory. also, you can do tag by using plugins: from Facebook to your blog vise versa. pieces of software that comes with basic package, you can search and add piece. for example, we need install plugin to use an activate markdown.
if you want to own your own wiki, so you should be able to control it. so, you need to have plugins.