The use case here is to allow rendering multiple tasks (or date range data) that might be overlapping by switching them to different rows within the same category.

An SO question was asked in this regard: https://stackoverflow.com/questions/55624319/highchart-gantt-chart-no-overlapping but it appears that the provided solution can't be generalized, see this other SO question: https://stackoverflow.com/questions/59809680/highcharts-gantt-avoid-overlapping-tasks/59824943?noredirect=1#comment105857552_59824943

I think that being able to provide data in a format similar to the first SO question, that is to specify a y value or other value to represent the category row index is a good solution.

As a side note, I posted another SO question (https://stackoverflow.com/questions/59863987/layout-of-gantt-chart-with-linkedto-series) where the result might get close to what is asked for here but we should be able to have better control on the category height and the distance between rows.