Sometimes it seems necessary to use words like "obviously" or "of course", otherwise a setting-up part of my explanation will be rebutted as condescending with "but that's obvious", and the rest, my actual point that follows, will be ignored.

If I acknowledge that something is obvious to both of us, there's a chance that the listener won't think I'm being condescending and will instead give enough benefit of the doubt to keep listening until the conclusion.