I suppose this is because of the uncertainty and the projection of what adults believe themselves - and thus their daughter - to be capable of. ... It could also be that they did that because they were witnessed and did want to spare the stress saying "no" to her...
... As I read it so far, a vicious circle seems to have developed, so that parents and the child can come into less trusting contact at all. The child feels, the parents are tense.
It is not easy to criticize... Therefore the question would be interesting whether your criticism could not be one that the woman already heard elsewhere and is now confirmed by you. There is a risk of making oneself unpopular and even provoking unfriendliness and counter-talk. To accept such feedback in a positive way at the moment of its creation is rather rare. I have seen that such things usually happen afterwards and are not necessarily brought close to the person who gave the feedback.
Didn't you feel the same way when you got criticism, you couldn't respond positively to it at that moment, yes, you even got angry and yet days or weeks later you found something helpful in it?
I once had a situation with a friend in which I asked her what motivated her to formulate the demand towards her son (because I felt a lack of trust in her son). Thereupon my friend reacted very unfriendly, as my question had offended her. But if my objection led her to think about my question later on, that was the price for bringing her displeasure upon me.
I must admit, however, that my question was coloured by the fact that I did not like what I saw and that my disfavour was the cause of her reaction towards me. If I had been less clumsy and had cultivated openness to results instead of my judgement, the situation might have been less uncomfortable.
There's no guarantee, but there is a probability. Sometimes a critique goes well, sometimes not...