And good marketing will help the 1.2x demographic discover that there's an improved solution while not worrying about the .8x demographic (or actively disqualifying them).

This thread is doomed to failure because half of the people are imagining the perfect altruistic, benevolent, competent marketer, and the other half is imagining the scummy, scam artist, and the actual answer is the tautological "good marketing is good and bad marketing is bad."

I've more than once seen a new database company grow from nothing to a serious business by being 2-5x for one narrow set of users and 0.1x-0.5x for the rest, but being sold as 2-10x for everyone. Most of their market doesn't end up coming from the people for whom they're actually a decent choice, because capturing even a small amount of the larger market is more valuable than 100% of that tiny market segment. Trying to deprogram people who've fallen for the marketing can be really frustrating, if you're trying not to be saddled with subpar crap that's going to make your life harder.

Mongo and Neo4j come to mind as examples of this.

Odd comparison considering graph databases are incredibly niche wheres you could argue document is basically just relational with embedding and with a different query syntax

Well, except it's Good Marketing is Good and Bad Marketing is a wretched hive of scum and villainy.