You were counseled right about chambering a loose round. The likely result will be a broken extractor in some models. Kahr comes to mind. Don't ask me how I know this.
I have done it repeatedly with Sig, Para, Kimber's, XD's, M&P's, Glock's with no ill effect. Never owned a Kahr. Never have had a broken pistol extractor. Now that I say that it will happen the next time I do it.