And you would too. You would, and have, ranted about things with your ex. Did you expect her to rant about her son AFTER she'd likely already had a talk with him about leaving his things? Did you expect her to rant TO her son about dad vocally refusing to mail them back? Instead, she ranted HERE, about him saying he wouldn't mail them, or wouldn't do it in time anyway, BEFORE he actually did mail them, and AFTER she'd likely already spoken to her son about the need for keeping up with his things. Her EX was the only part of the equation left. She could handle it with her son by talking to him. She could NOT handle it with the ex by talking to him, nor by talking to her son about him...so she came here.
But of course taking the common sense approach often eludes you.