Maximum number of indoor modules

Each weather station can apparently communicate with a maximum of three indoor modules. I find this number far too low and recommend connecting approximately twelve indoor modules. This is the only way to adequately monitor a large house.

Or is there a technical reason to only allow three indoor modules?

From the help page:
Each smart weather station can accommodate a maximum of:
1 outdoor module (included with the purchase of a smart weather station).
1 smart rain gauge.
1 smart anemometer.
3 additional smart indoor modules.