Sure it is.
I don’t know about you but accepting a friend’s post on Facebook for others to hire you for design/development work as compensation, yeah, that won’t pay your bills. Especially since they are not obligated to do so. You’ll be waiting for quite some time, probably in a box out on the street if you go about it that way. Charity work is a different story. You’re doing work for a cause.
In my experience, individuals just starting out tend to charge little to nothing because they are not educated on how to go about it properly. No one teaches you this.
However, I am not saying word-of-mouth is not valuable because it is. But charging nothing in the process will not allow you to pay your expenses.