I don't think you will find many that agree with you that a 2 party system means the same thing happens regardless of winner. I'd agree that foreign policy of the US, with few exceptions, tend to be pretty stable, but domestically it's quite a bit different. I also think that what you say applies more to the Presidency, but local elections matters more in terms of who actually wins and is arguably more important to people's everyday lives - but everyone focuses on the big election, often to the detriment of the other elections. I think that's the wrong way of looking at it, the "body count" needs to be compared to what would have happened otherwise, not to each other. In these types of things, we need to be looking at the trend lines - because absolute counts hides far too much context. It's why early on when people said "Swine Flu killed more people!" were pretty silly since COVID-19 reached those death counts much more quickly and ignoring time in their analysis makes very little sense.