The connection would be secondary. In FPTP, the blue team and red team play for “all the marbles”, so more divisive language and negative campaigning are effective. In RCV/AV systems, being second choice on lots of ballots is a valid tactic, so in theory less negative campaigning.

Although this effect is likely as described, I can’t help to think that in recent years the divisive effects of social media have far outweighed it.

I’ll also point out that RCV/AV eliminated the spoiler effect. It also can lead to a “gateway voting system” to STV, which is probably my favourite.

IMO, FPTP << RCV/AV/IRV << MMP < STV.