Suppose I were a laptop manufacturer, I could just make the exact same laptop as some other laptop (same specs, heatsink capability etc.), and just switch to using better thermal paste, and I would instantly get up to about 10°C lower temperatures with very little increased cost per unit and zero R&D cost. I don't see how a "they don't care" explanation is valid. OEMs spend time and money engineering heatsinks, fans, etc, sometimes even use fancy stuff like vapor chambers and pompous gimmicks like GORE. So while they're at it, why don't they also use better thermal paste for an easy performance gain, better user experience, and a competitive edge? It seems like a no-brainer to me.