However, many don't seem to get why it is bad even after an explanation simply because the service is free or easier to set up than one on your own hosting.
Stories like this one are all too familiar: Google takes down man's blog, erasing 14 years of work | Fox News
That is why you don't put all your marbles in one basket if you can avoid it. The same goes for all free blog services.
Facebook is another example of something to be careful with. More and more "how to succeed online" training products are pushing people to set up pages and groups on FB. FB groups are replacing some forums and some folks don't even have a website because they rely totally on FB groups or pages.
Currently, there is no way (outside paid resources) from what I understand to back up an FB group.
Of course, you can use FB pages or groups - I do. But you'd be wise to figure out a way to back up your data and keep it safe. This applies even to resources on your own hosting.
So no matter if you rely on Blogger, Wordpress.com, or FB pages/groups, when you wake up one morning to discover it's all gone bye bye, you only have yourself to blame. Think twice before you wind up like the guy in the news article.
Which free service have you given too much control over your business?