Complex sentence: The convention came as result of the problem that, in competitive auctions, the opening bidder would often like to show 3-card support for partner's suit, but distinguishing between 4-card and 3-card support is important.
Split into simpler sentences: The convention came as result of the problem that, in competitive auctions, the opening bidder would often like to show 3-card support for partner's suit. However distinguishing between 4-card and 3-card support is important.