Creating outlines for text can be important when you are submitting native InDesign, Illustrator or Photoshop files to your printer, because these files may use fonts that are either not available to the prepress department or are different versions of the same fonts. In the latter case, text may reflow in undesirable ways and cause nasty (and expensive!) surprises. In the days before OpenType, there could also be cross-platform problems, so that even if you sent the actual font files along with the document they might be unusable on the remote system.
PDF mostly solves this problem by embedding the actual font data and fixing the text so that it won't reflow, regardless of what type of system receives the file. Do not use "High Quality Print" for a PDF you're sending to press. This is an RGB preset designed for desktop printing or other situations where RGB output is needed.
There are two situations where you might have to outline type: when the font license prohibits embedding (so that it won't be in the PDF) and when you are submitting native files but the printer doesn't have the necessary fonts. Most font licenses do not permit you to send a copy of the font to someone else who has not independently licensed that font, a legal nicety that's often ignored but is still valid and can have consequences.
The warning you saw about outlining being unsuitable for body text applies when the document will be printed on low-resolution printers, such as office laser or inkjet printers with a maximum resolution of 600 dpi or so. On this kind of printer, outlined text prints too bold because the hinting information, designed to maintain the "look" of the text, is thrown away when it's outlined. You print provider uses an imagesetter, which outputs to a negative or directly to a printing plate at a resolution of 2400 to 2800 dpi. It doesn't produce the "fattening" effect visible on lower-resolution devices.