Thank you Elegran!
I stepped away from the thread after a while, as it is exasperating when people don't read the thread, and I have clarified several times that this is not about dinner parties or house guests. The thread on MN was similar - the OP asked if she was being unreasonable to offer the lasagne (vegetarian to cater for non-meat eaters) and to resent friends telling her they'd prefer her to provide 'nibbles'. The replies were largely about what individual posters prefer to eat on Boxing Day, which was irrelevant to the question, and rather self-absorbed.
I don't understand why I have been called rude for not finding out what people want and providing it, when this the situation I described has nothing to do with social hospitality.
More generally, it is interesting to see how opinions differ about how far a host should go. If someone has allergies, I think it's up to them to make that clear when accepting an invitation that involves shopping and cooking, so the host hasn't wasted time and money on something they can't eat, but if they prefer biscuits to cake, or tea to coffee and their preferences are not offered, it is rude/entitled to assume that they have a right to ask for any refreshments in the house.
I also think that a good host will think ahead, and if they are hosting a social event such as a coffee morning will get in both tea and coffee and a a variety of snacks, but they should not be expected to get in unicorn milk and angel-kissed cloud cake on the offchance that someone will want it, particularly if the 'guests' are virtual strangers. FWIW, I always have a range of flavoured hot chocolate and several varieties of herbal/fruit teas, but that's because we drink them, not in case I offer coffee at a meeting and a man I hardly know fancies tea instead, but only if I have one with red fruits.
Before deciding on a menu for a dinner party, if the host doesn't know about dietary preferences/restrictions then it makes sense to ask, but having ruled out meat, dairy or specifically disliked foodstuffs they should be free to choose what to cook, and the guests should accept it gracefully.
None of the above applies to family and close friends. I know what they all like, and in any case my immediate family help themselves to anything they like (with my blessing). Close friends know they can ask for what they fancy, and if I have it I'll happily serve it up. I have one friend who 'likes a drink' and will sweep aside a suggestion of a hot drink at any hour of the day, and make straight for the wine rack or fridge to get a bottle of something. I don't mind, as I know that if I drank alcohol I could do the same at her house, and if I were saving the wine for something, or if it belonged specifically to Mr Dog I could tell her with no offence taken.
A lot comes down to the relationship between the host and the hosted, I suppose.