Smart use of bold text can help make a slide clearer. Overdoing it takes out the whole effect.
Why do people fall for this? If you start at your own chart for hours, rereading it, changing the line breaks, bolding and un-bolding text, you become convinced that the text is super clear. It is, for someone who has studied it for a long time. Not for someone who looks up from her phone and sees it for the first time.
P.S. Use ctrl-B (Windows) or cmd-B on selected text in SlideMagic to make things bold.