I disagree with that. While a "IF Sub 1 activates THEN X" sub can usually be done on a different manner (or has dubious utility), there have been many times where a "IF X AND Y's first sub activated A1 THEN Z" sub saves a gameplan. If said sub, for example, has different possible action clauses (X on the first instance, Y on the second etc) and you want to activate your second sub regardless of the instance the first was activated, then subbing for sub activating is fair.
Also, as a chance sub, you can always put AND NOT sub 1 doesn't activate, have both nots cancel each other and reach the same result.
It is frustrating as fuck to know your opponents move, know how to counter it and no being able to do so because some obscure ruling about subs doesn't let you. If looping is a problem just add a "if the substitution ends up creating a loop, it is considered illegal. If more than one substitution creates the loop, the one from the player that ordered last is illegal. If both players ordered at the same time or if both substitutions were done by the same player, both are deemed illegal" general rule. Punish the ones that can't sub properly, the ones abusing subs. Don't punish the ones trying to use all the options available to get a good strategy going.
Also, as a chance sub, you can always put AND NOT sub 1 doesn't activate, have both nots cancel each other and reach the same result.
It is frustrating as fuck to know your opponents move, know how to counter it and no being able to do so because some obscure ruling about subs doesn't let you. If looping is a problem just add a "if the substitution ends up creating a loop, it is considered illegal. If more than one substitution creates the loop, the one from the player that ordered last is illegal. If both players ordered at the same time or if both substitutions were done by the same player, both are deemed illegal" general rule. Punish the ones that can't sub properly, the ones abusing subs. Don't punish the ones trying to use all the options available to get a good strategy going.