I would extend it to - avoid transfers anywhere in North America (including Canada). US and Canadian airports are pain in the ass regarding customs and immigration. Better to transfer in Europe or Asia and fly directly from there.
Domestic connections do require security, connections to US generally require preclearance security. Connections from most other countries also go through security.
The odd thing is that they don't separate arrivals: so you'll mingle with worldwide arrivals, go through transfer immigration with everyone else, and finally you show your boarding pass and get routed either to the departure gates, or to security, based on your boarding pass.