Index funds, pair traders and portfolio managers care about the basket's net exposure, not each line. Basket tools handle the whole list, balancing cash, minimising residual exposure and often quoting a single commission.
The risk being managed is legging: if half the basket fills and half does not, you are left with an unintended directional bet.
Example: a fund tracking an index must invest a $50m inflow across 500 names before the closing-auction. A basket order sends 500 limit-on-close orders sized by weight in one message. Doing it by hand risks a missed cut-off in a handful of names and a tracking error that shows up in the fund's monthly report.
Related: algorithmic-order