The interesting thing about Merchant Princes is that not only is it not a "wish-fulfillment" portal fantasy, but at least in its setup it's a pretty severe deconstruction of the bog-standard wish-fulfillment changeling/portal fantasy. Consider: it's about a young woman from our world who suddenly discovers that her real parents are powerful nobles from a medieval-type world with apparent magical abilities and she is betrothed to a prince; it doesn't get more standard changeling-fantasy than that. But then it turns out that a parallel world with medieval-level technology and society is a squalid hellhole where a noble family is basically an organized crime gang and her only value to them is her ability to create a political alliance by marrying who they want her to marry and producing heirs. So it's not so much avoiding the standard wish-fulfillment tropes but actively subverting them.

Then it all turns into economic SF.