timethief: The reason for electing to open links in a new tab/window is to avoid destroying the user’s information. Your user has expended effort to display whatever page they’re reading. It is arrogant to assume that you should throw that information away whenever the user seeks amplification of a point or wishes to consult another reference. If the user wishes to dismiss their data, then they should make that choice, not you.
Most links in blog discussions are like subroutines, rather than execs – they exist to provide supporting information for the argument, not as destinations. One expects the reader to open the supporting information in a new page, read it, then dismiss the page to return to your original argument.