Shroud of the Avatar has been selling players the right to run their own towns for a while, which is a good thing. It also does create certain limitations, though, since if you have too many player towns out and about, the world feels less like a fantasy adventure realm and more like the New York City metro area. So the designers decided to hard-cap the number of player-owned towns with overland map access at a solid 230 towns.
The towns then promptly sold out.
Of course, the cap does not mean that more player-owned towns cannot be purchased, merely that any further towns must be connected to another town that does have overland map access. The details are available in the official announcement. You can still buy a town if you want to, but your ability to get random foot traffic will be slightly curtailed.