I think its completely normal. Not that I have ever actually been to a dinner party but we have been to parties where everyone contributed a bit and in return there was great catering and lots of booze. I don't see how it is rude.. at all.. I mean it genuinely puzzles me that it would be thought of as rude..
But then nobody I know has really any money at all so it would be near impossible for anyone to afford a big party otherwise.
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