To someone, my responsibility might be answering the doorbell quickly when Amazon drops off a package.
To another, it might be how responsive I am to email.
These are in conflict, and sometimes it’s worth missing an Amazon package to finish an important email.
If you have struggled to interact with people who are different than you, that is also part of the human experience, not something we need to devise measurements for.
IF is a tool mostly to remind high IF people to cherish the value of both real and imaginary experience, and a tool to help people who dwell mostly in either realm to respect each other. If a high IF person forgets to respect the real, he's liable to forget his wedding. If a low IF person forgets, he's liable to miss out on the wonder and value of abstract thought.
While provocative, that argument does not take into account the development of the brain. Processing early experiences are far different from the ones when the brain is fully developed. This includes the storage of memories (knowledge).
Time spent in "infinite fun" (as they call it) has no value because it has no impact on what happens in the real world, hence the importance of remembering where the off-switch is. It's about having an effect on the world, not the world having an effect on you.
Someone who spends a lot of time (and in all likelihood is wired to spend a lot of time) thinking about their work is not wasting their time; they are preparing to have an effect on the world.
And you didn't say anything about "real-worlders" having humility and respect for the other party.
I think a reasonable person infers a value judgment from those two things together.
If this world is a simulation, and someone among us is the player-character, forgetting that there is an off switch is a feature for them that increases immersion by making any failure to suspend disbelief (which I as a probable NPC suffer from regulary) a moot issue. As long as we think that this is reality, its believability is subordinate to its survivability.
If this world is a simulation knowing the nature might let us work with it better. Hacking the universe (maybe or maybe not if a simulation). It would in some ways just become an extension of physics (in effect).
This gives me an opportunity to bring up a favorite story of mine.
Wang's Carpets by Greg Egan: https://en.wikipedia.org/wiki/Wang%27s_Carpets