I'm happy to detail what I know of the history but most of the individuals that began the history of these decisions are no longer here, so we continue with the best methods which are in-keeping with the history - Garrett was just in-keeping with history.
The general idea is to preserve the "level playing field" - the equipment in use should never impart an advantage.
Obviously different people have different abilities and that individual ability is what makes us different (not a part of "level playing field").
Equipment should be original where possible. Over the years this has become
very muddy and is where this submission sits.
Before 2014, TG operated a Referee system - the referees viewed the footage and checked against the rules.
Before 2014, such third-party commercial multi-carts were simply banned. Hacks of consoles were banned. This was the base ruling.
Before 2002 the
Cuttle Cart was banned - something that permitted loading ROMs on the Atari 2600. It was banned because the ROMs were altered (changed to audio) and so not original.
In 2004 the the
Cuttle Cart II was accepted because
the device made no alteration to the original ROM. It was up to the player to use the original ROM. Since the there have been many such devices and, for the Atari 2600, the Harmony is the most well-known at TG.
Over time, TG kept a list of those devices which were permitted:
https://www.twingalaxies.com/showthr...ti-Flash-Carts . Anything else was still banned.
2013 TG died.
2014 TG resurrected as a stale scoreboard (copy of old scoreboard only).
2015 TG started accepting submissions via TGSAP. There are no Referees at all. Everyone in the community is an "adjudicator". Everyone must evaluate the rules, including all the hidden rules that the referees used to keep because the "level playing field" is the only correct way to compare scores.
(Lots & lots of history, decisions and weird stuff missed.)
One important thing: there are always exceptions! Very confusing!