Fair enough, though I do think this can still help with any broader approach to changing their overall mentality.

A moment of consensus on its own might not be enough to sway someone, but if they hear someone try and contradict what they had recently agreed on, it can then make them feel more cognitive dissonance, and potentially make them at the bare minimum just stop and think for a second.

If someone else is later trying to sway them in some way, it's going to be easier when that person says something, and they can think "I remember saying something similar" rather than "this is the opposite of what I already believe."

Plus, there's also just the sort of "exposure therapy" factor to it, as well. A lot of people are radicalized to believe that the "opposing side" is pure, limitless evil, and that they hate you and want you dead, so just interacting with them can be enough to help slowly deradicalize them.

For example, this Pew Research article states, regarding the likelihood of people to support trans people's existence:

"Though Republicans who know a trans person are more likely than Republicans who don’t to say gender can be different from sex assigned at birth, more than eight-in-ten in both groups (83% and 88%, respectively) say gender is determined by sex at birth. Meanwhile, there are large differences between Democrats who do and do not know a transgender person. A majority of Democrats who do know a trans person (72%) say someone can be a man or a woman even if that differs from their sex assigned at birth, while those who don’t know anyone who is transgender are about evenly split (48% say gender is determined by sex assigned at birth while 51% say it can be different)."

But of course, that isn't just limited to acceptance of people by gender. It also applies to race, social and economic status, recipients and non-recipients of welfare programs, people working in different industries, etc.

Again, not saying it's at all some magic universal way to change someone's mind, or that on its own it's necessarily a factor that can override their overarching condition, (hell, that quote from before shows that it had a much smaller impact on republicans than democrats even given the same exposure) but the more and more this happens, the stronger and stronger an effect it has overall, and I'd say that alone makes it worth doing.