When using a spincast reel, what is reduced due to its design?

The design of a spincast reel incorporates a closed system where the line feeds through a cone-shaped guide and a cover. This design significantly minimizes the chance of backlashes, which occur when the line tangles or winds improperly on the spool during casting. Unlike open-faced spinning reels or baitcasting reels, which can allow line to escape uncontrollably if not used with proper technique, the spincast reel's features help to keep the line in place and organized, thereby reducing the occurrence of backlashes.

The other options do not relate directly to the primary function of a spincast reel. The weight of the line, the length of the cast, and the size of the lure are factors that can be influenced by various external conditions or other types of gear but are not intrinsic characteristics altered by the spincast reel's design itself.