At an offline tournament every competitor plays on a machine the organizer built. That standardization is a competitive integrity measure with a long list of practical requirements behind it.
Identical machines remove a variable
Online play happens on whatever hardware each player owns, which introduces differences in frame rate, latency and display behavior that can matter at the top level.
An event supplies matched systems and displays so that a lost duel is attributable to the player rather than to a machine that rendered a moment later than an opponent's.
Achieving that means sourcing dozens of identical configurations, imaging them the same way, and verifying they perform the same under load before the first match.
Peripherals stay personal but get checked
Players bring their own mice, keyboards and headsets, since muscle memory is built around specific hardware and forcing a change would distort results more than standardizing would fix.
Organizers usually inspect those devices, because programmable peripherals can execute macros that automate inputs the rules require to be manual.
The typical compromise permits personal devices with onboard settings restricted to sensitivity and lighting, with any scripting capability disabled or checked at station setup.
Configuration files are controlled
Competitive titles allow deep configuration, and some settings confer advantages that the developer never intended, such as visibility changes from stripped effects.
Events therefore define a permitted configuration and load it on each station, allowing players to restore personal binds and sensitivity within those limits.
The process is slow, which is why stations are prepared long before doors open and why a configuration dispute can delay a match while officials verify a file.
The network is built for the room
A tournament network is isolated from the venue's public connectivity so that match traffic never competes with thousands of attendees using their phones.
Servers frequently sit in the building, which lowers latency to a level online play cannot match and changes how some game mechanics feel to the competitors.
Redundant links and spare switching exist because a network failure mid-series forces a restart, and restarts consume the schedule the whole broadcast depends on.
Isolation extends beyond the hardware
Players on stage can hear a crowd reacting to information they should not have, which is why competitors typically wear noise-isolating headsets under audio playing masking sound.
Phones and outside communication are restricted during matches for the same reason, and coaching is limited to defined windows rather than allowed continuously.
All of it serves one goal: making the offline result depend on what happens between the players, which is the entire argument for holding events in person.