Comment by Panzerschrek
5 hours ago
PVS requires some hierarchical scene representation with no seams between walls. I know no other way to build such representation other than BSP. But BSP works fine only with pretty low-detail map geometry consisting of brushes. No large detail meshes or terrains can be used with it. If a game has a lot of open spaces or semi-open spaces it's nearly to impossible to build a BSP for it.
PVS does not require a hierarchical representation. You can use any representation you want. In fact the one in the article itself is not hiearchical.
In practice many useful representation can be built only in a hierarchical way. Unless you want to force artist/map makers to split their maps in regions manually.
All Source / Source 2 games still use both PVS (bsp/octree) and pre-baked lightmaps. Of course, they’re quite notorious for the staticness of their environments.