I disagree. First of all think your question is patently incorrect and built on a false premise. It is possible to have an immersive experience in your inner world; full stop. It's just not possible to do anything other than automated, reflexive and rudimentary physical tasks while doing it. Though again, it is possible to do those things. This all without a tulpa.
Here's the thing though, perspective is a trick of the brain communicating between its various sections. There's good evidence to suggest that all of the data we are not conscious of is all still being processed but just not passed to the segment of the brain we are being rendered in. Tulpas don't render any data at all when the brain isn't focusing on them, but empathy works by creating a complete picture of experience then dissociating from it, ie, muting the input to your senses as it is passed through communication centre of the brain.
It seems more likely to me that tulpas are experiencing a different perspective from us by default that we are being removed from, to my eyes. Also, I'd encourage you to give me any sort of real data that suggests this isn't the case. You seem to naturally presume your own perspective is the only one the brain is actually rendering, when I think that is inconsistent with what we observe the brain to be doing when it processes things like empathy.