I think it is only a few terminally online people that object to this. In real life locals object to people coming in and buying second homes or renting out airbnbs, not new people moving into the area permanently.
Which, to be honest, is not totally unjustified, these places are wonderful and people whose families have lived there for generations are finding themselves pushed out by the rising property values caused by the migration of people out of the rich cities and into their communities.
It's unfortunately a feature of our system- if you don't have money you don't get to live in good places. People are just justifiably unhappy with that particular feature acting on them.
I know a guy who moves from CA to Idaho.
He complains people don't maintain their houses nicely enough.
He complains the dirt roads aren't graded well enough.
He complains that the super market doesn't have what he wants.
He complains that the way they do excavation is wrong (he's a septic guy by trade).
At literally every turn he complains that the locals are doing it wrong.
I've told him that the problem probably isn't the locals. (And I concur with what the other guy said about rising property values destroying communities.)
My parents now live in a red flyover state and complain about foreign Californians making everything too expensive and changing the local culture. To put it in perspective, my parents who are complaining have lived ~3x longer in California than they have in their new red state.
I love them, but not all of the people complaining about Californians are the people it would make much sense to get complaints from.
The reality of the matter is that the insane population growth of the 20th Century led to some pretty haphazard development (e.g. CDMX’s never ending sprawl).
This has made areas with livability amenities (e.g., walkable safe neighborhoods) relatively rare all things considered.
For various reasons, certain areas with good amenities remained isolated from broader real estate markets (e.g., living in CDMX would seem laughable to an American in the 1980s based on crime statistics alone).
Because of COVID, a lot of those areas are now a part of larger real estate markets.
The people who live there now realize that they can’t afford the prices that the larger market brings, so acting in self interest, they try to remain isolated from the market.
(In the vein if SF experiencing the worlds problems a decade before anywhere else) This is basically the story of SF’s Mission district over the past 20 years and why you’d see ridiculous things like people protesting new development because it had floor to ceiling windows.
It’s a weird phenomenon, but one that most people on this forum can’t really relate to.