I was told that 'congratulations' went to a person who had achieved some accomplishment, and it was offered to grooms because they had persuaded their intendeds to accept their proposal of matrimony. One wished the bride happiness, since it was assumed that she had done nothing to lure the groom into marriage. And yes, even back in the day, no one believed that brides did nothing to persuade their fiances to propose. 
Yep, this is what I've heard too.
On topic, what a weird woman! She berated you for not saying "Congratulations", but when you did say "best wishes", she still went over the edge! I suspect she was spoiling for a fight. If you HAD congratulated her at the outset, she probably would have berated you for being presumptuous or something.
I agree with PPs that the woman's behaviour re the OP, in this matter, can only be described as lunatic. I'd perceive, however, that -- nutty though she likely was -- she was not totally alone as regards attitude to the word "Congratulations". It seems that there is a small, but discernible, number of people who are extremely hung-up on what they see as use of that word being obligatory in certain situations -- expressing the same sentiments any other way, without specific use of the "c-word", being considered heinously rude. Early this year, there was a thread on the eHell blog featuring this matter. It emerged there, that some people have this quite fanatical conviction about the obligatory use in some circumstances, of the "magic word": such cited, were when responding to a woman's announcement of her pregnancy; and at weddings -- in the particular example given, it was not re "say it to the groom, but not to the bride", but because the "offender" gave thanks and good wishes to the parents of the bride, but failed actually to say the "c-word".
Such very extreme sentiments regarding one particular word being used, or not used -- failure to use it, apparently seen as an etiquette violation on the level of (the most disgusting and disruptive conduct at such a gathering, that one can imagine) -- strike me as bat-poo crazy. It would appear, though, that there are a few people -- some of them, presumably, sane in other respects -- to whom this thing is that important: and they feel that they must loudly proclaim their outrage if anyone gets it wrong. If etiquette in general supported such "nuclear" responses, to things which were so trivial -- I would be in favour of the abolition of etiquette.
