It does sound like more of a Democrat defensive play against all of those little splinter Leftist parties that keep popping up. Green Party, Working Families Party, Socialist Party, etc.
Yes, and they are better at that than we are. In Maine we now need a dozen conservative splinter groups to run candidates, because that brings more voters to the polls, and if those voters rank the republican above the democrat, the republican will win those votes as the splinter candidates are eliminated.
There is nothing horribly bad about the instant run-off, but it does require a new strategy, one the democrats already had in place, and which the republicans are lagging (in Maine).
As someone noted, if we had instant runoff in Virginia, Dave Bratt would have won election, because it is highly unlikely the libertarians would have picked the democrat above him as their second choice.