Vampyr, on 2016-January-14, 04:31, said:
What types of hands would usually bid 3♣ without a 3-card major (assuming that you have both 3♠ and 3NT available to show various minor-suit hands?)
I would bid 3
♣ on such mundane shapes as (42)(43) and (41)44. 3
♠ and 3NT aren't going to help you when you have (41)(35) shape and just want to see whether you have an 8-card major fit; and even when you are willing to go beyond 3NT to show the minor they seem awkward. You can vary this very frequent shape to get less frequent ones like (41)(26), (40)(45), (40)(36), etc. etc. Sometimes I might even bid it on a (31)(36) or (30)(46) shape. Oh and I've not even mentioned (42)(52)!
We're not looking at one crooked tree here. Half the forest has been burnt down.
So in contrast, the gains from this convention are going to need to be amazing. Instead, the OP would like to gain... absolutely nothing. If you rebid 3
♠ instead of 3NT on the no-major hands from opener your gain is negative - responder is going to need 3NT as "to play" so you don't gain any space and meanwhile you've given the opponents a free double or non-double of 3
♠. Let's say you were more creative and decided to play 3
♠ as showing a hand with a 6-card minor. The one additional slam per 10 years you manage to bid is going to be offset by the 30 other times you bid this and simply helped the opponents defend better.
I agree completely that people deserve respect. One way to show respect is by not wasting their time, for instance by telling them that you play "upside down carding if global warming is real, standard otherwise" or by proposing ridiculously bad conventions on a discussion forum.
"One of the painful things about our time is that those who feel certainty are stupid, and those with any imagination and understanding are filled with doubt and indecision"
-- Bertrand Russell