This was also a reason used to keep blacks and minorities out of predominately white neighborhoods. Many people believed that bringing blacks into a neighborhood would devalue their homes. Once a black person moved into your neighborhood - "there goes the neighborhood".
It was a self-fulfilling prophesy because once blacks moved into a neighborhood, all the white families would move out ( white flight ) which caused housing values to collapse since there were so many more sellers than buyers.
On the flip side, it's why gentrification increases home values. As blacks/minorities are kicked out of the neighborhood and it becomes more white, it attracts more whites to move in. More buyers than sellers. Gentrification is the exact opposite of the white flight phenomenon in america.
No, it was the first in the US, as described in the article I linked. I agree it's not the only reason, but I think it's important to mention the racist origins every time someone gives another reason for single family zoning.
[Edit: I originally said first in North America. I misremembered what the article said. Changed to US to match it. Wouldn't surprise me if first in North America were also true though.]
SFH has existed heavily in New England, Canada, Iowa, pretty much every where in North America in spots where there are very few black people. Even heavily black neighborhoods like Baldwin Hills (aka Black Beverly Hills) historically had quite a bit of single family zoning. I think if that thesis was true you'd see large historical discrepancies with SFH in different states but you really don't.
I grew up in a suburban white town next to a city that was 95% white and our town had a lot of NIMBYs who prevented condos from going up. I do no think it was because they were cool with 95 white people moving in but scared of 5 non-white people. I think they just knew that it was bad for property values (for supply/demand reasons) + property taxes (for budgetary reasons) and were selfish.
The only reason I push back on this is because I don't think its helpful. I live in LA and the most common cited arguments against SB9/SB10 was that it would hurt "middle class minorities in south LA" and the representatives of these areas all voted against the bill (presumably because their biggest donors are black+hispanic+white landowners in these areas)