Due to the impossibility of becoming "landed gentry" in the modern United States of America -- in the same way that being knighted is likewise impossible here -- using the phrase to describe a group of people is taken as intentionally misapplying a metaphor to insult, divide, denigrate, and bully the target group.
When folks misuse a term like "landed gentry" that tells me that the argument they want to signal is that "those people" are evil and bad while "our people" are good and honorable. Therefore, those people's homes should be taken away and replaced with high density housing for our people. That's certainly an argument. I personally don't find it particularly compelling, but I'm not an SF voter.
As far as MWOD, that publication might consider reviewing whether or not they should be making such low quality definitions publicly available -- it's a sad day when you're upstaged by Urban Dictionary [1].
https://www.urbandictionary.com/define.php?term=landed+gentr...