Last i’d heard, ‘they provided an interesting alternative way of thinking of the problem’ but provided no unique insights or additional testable behaviors. The folks using the alternative theories ended up being able to formulate them more directly using other (‘normal’) physics later. Do you have a cite for anything contrary to that?

It doesn’t help that when something does finally seem experimentally provable (Craig Hogan noise for example), but then gets tested and seems disproven, then it gets ‘removed from Canon’ as it were and ‘is not string theory’.