Wordpress.com is a free website hosting platform that can allow users to build their own Wordpress website / blog without need to look for other hosting in order to host Wordpress from Wordpress.org
Pro Optional free hosting
WordPress offers free hosting under a wordpress.com subdomain. This option eliminates the need for setting up the CMS yourself and is reasonably secure, as WP uses multiple servers to back your site up. Additionally, for a fee, you can even set up your own custom domain name.
Pro No installation and configuration needed
Unlike Wordpress.org where users are required to find their own hosting services, install to their hosting services and configure the settings, user can use Wordpress.com to create their own Wordpress website without any hassle and without any installation or configuration steps. Any hosting and configuration will be fully managed by Wordpress.com, so user no need additional actions.
Con Too many amateurish, insecure, outdated, unmaintained, incomplete or useless plugins
True, there may be some plugin for every functionality you require. However if you take a more detailed look at those plugins they are either outdated, made by some hobby programmer (i.e. no in-depth testing, no security audits, no code reviews, hacky, unmaintainable) in their spare time (and don't get me wrong: I adore everyone giving something to the community; but many of these plugins are just unusable for serious business), incomplete (regarding multi-language capability, an author of a famous Wordpress form builder plugin responded something like: "Well, maybe sometime"; seriously, man?), insecure (e.g. recently there was a serious flaw as a buggy plugin is used by many themes) or often need much hacking to finally get the correct functionality that YOU need currently.
Wordpress by default allows commenting on pages, any page. Even if you turn commenting off for a page bots can still access the commenting endpoint; even if you use a 3rd party commenting system such as Disqus. Wordpress comes with an anti-spam filter called Askimet which does a pretty good job but not perfect.