This doesn't really say anything about religions. Constructions company can build a lot of thing. Temples are just happen to be good business at that time.
But temples are almost uniquely good for construction companies.
- the more ornate, the better
- unlike palaces, every town needs at least one, and if you're polytheistic, so much the better
- extremely price-insensitive clients who are content to wait generations
- you can probably easily bulldoze both structures and local opinions that get in the way of construction because you're building for a cause everyone's supposed to worship
