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...
[1]: https://www.merriam-webster.com/dictionary/landed%20gentry
It's debatable whether MWOD is guilty of playing a dangerous game of propaganda by peddling low quality definitions online with high SEO. They have an ethical obligation to not revise words out from under the population unless, of course, they are a non-neutral party with a particular agenda.
It's not fair to people, like yourself, who want to advance strongly-felt arguments to spoil those arguments with terms based on these weak definitions just because they showed up high in Google Search results.
As the terms our society uses to communicate continue to degrade into group-specific definitions, we will generally lose the ability to communicate effectively across groups; and, in turn, the ability to compromise and negotiate in good faith.
In other words, one's political opponents might interpret a speech differently due to the use of a different dictionary rather than (merely) disagreement with a particular argument.
To glimpse at one dystopian future, consider that the recent phenomenon of declaring one's personal pronouns might soon include identification of one's personal dictionary, one's personal thesaurus, one's personal collection of idioms, and one's personal grammar.
Come on now, let's at least use the right words. These folks are "homeowners", not the wealthy living off of rental properties. Used improperly, that term is exclusionary.
[1] https://en.wikipedia.org/wiki/Landed_gentry