Basically every family? That doesn't seem right.
The wikipedia page you linked says that nearly all affluent families had dachas, making up about a third of the overall urban population.
Now if you're working for a prestigious institution in high-up position, that patch of land gets bigger, you may be able to pull together resources to build a summer house there and the whole communal garden might be a prime location surrounding a lake, bordering a forest and so on.