I don’t offer because what I consider homes to be worth and where the general market is, is too far apart. It would waste my time, the sellers time, and our agents time.
Also, should one accept my offer in the current market, I’d be instantly concerned that I don’t know something that they know about the property.
As for insulting offers, well, yes, you are insulting them to point. If the home is at or near market and the seller isn’t distressed needing a quick sale, an offer that is 30% below FMV, is an insult that says “I think you’re stupid and lazy”. IMHO. A home listed at 10% below FMV will move.
Of course, FMV has absolutely nothing to do with what 90% of the homes on MLS have for an asking price. FMV is the price that the homes that have sold are going for given their condition, location and tangibles.