LAN play required for all Major and tier-1 events; 128-tick (or sub-tick) dedicated servers provided by tournament organizer; Online qualifiers: minimum 50 Mbps connection, <50ms ping to server
Why people argue about this
People often assume that the "Network for all Major and tier-1 events must be LAN play required" rule means players can't use their own internet connections during these big tournaments, but actually it's about ensuring a fair playing field by eliminating variable network conditions that could give some teams an unfair advantage.