that's not ultimately true. remember, the person who named the kungfu as formless is JY himself; he is the storyteller, and therefore CAN recognize any kungfu in the book. (why? cuz he made them all up.) now, if JY calls a kungfu formless, then that must mean that it is formless relative to ALL the kungfu existing at the time; not simply because someone doesn't recognize it.A fight between A and B.
A: uses 'formless' KungFu, he shows an (infinite) variety of stances/variants/forms of ideas/motifs.
B: cannot see a (fixed) pattern of all those forms, he cannot classify it to a certain type of KungFu. From his viewpoint it is a formless/typeless KungFu.
the way you defined formlessness should give you a clue: "infinite stances/variations". in fact, this IS the essence of formlessness.
forms, or stances, were created by martial arts masters NOT because they needed them, but only in order to pass down the information to a learner. i mean, DGQB didn't sit down and go "okay, i'm going to need 9 codex for DG9J. lemme write them out and study them, and then i will know this kungfu." rather, DGQB noticed that he could break all weapons/palms/chi, and set out to figure out how to express that into words, thereby creating the sutra for DG9J. it's the same for ALL martial arts masters; they get a breakthrough in kungfu, and THEN make it into forms so that their students/the reader can understand what's happening. the reason why LHC strikes out with a "sword-breaking stance" of DG9J or YG does a "dead man walking" sadpalm is so that that WE AS READERS know what they're doing. to them, they're just following the essence of the kungfu that they've learnt. they're not thinking "okay, so this is when i'm supposed to use so-and-so kungfu".
therefore, to use formlessness is to rely on your own ingenuity, rather than following steps left behind by an old master. this was the main difference between yue buqun and LHC.