Here is an example scenario where this would be useful: https://jsfiddle.net/lanimelrok/6eodqvwy/

This has been asked throughout the years plenty of times. Here’s a few from a quick Google search:

https://www.highcharts.com/forum/viewtopic.php?t=16169
https://www.highcharts.com/forum/viewtopic.php?f=9&t=8952
https://www.highcharts.com/forum/viewtopic.php?f=9&t=41738
https://www.highcharts.com/forum/viewtopic.php?t=39380
https://stackoverflow.com/questions/26745540/how-can-i-hide-and-show-a-category-in-highcharts
https://stackoverflow.com/questions/32776861/how-to-show-hide-categories-with-checkbox-using-highcharts
https://stackoverflow.com/questions/42842553/show-hide-part-of-series-in-highcharts-base-on-x-axis-category
https://stackoverflow.com/questions/5721635/highcharts-toggle-a-category
https://stackoverflow.com/questions/38585005/how-to-hide-grouped-category-in-highchart
https://stackoverflow.com/questions/19956134/how-to-hide-show-a-column-in-a-basic-column-graph-of-highcharts
https://stackoverflow.com/questions/32776861/how-to-show-hide-categories-with-checkbox-using-highchart
https://github.com/highcharts/highcharts/issues/3118
https://highcharts.uservoice.com/forums/55896-highcharts-javascript-api/suggestions/3517780-show-hide-one-or-more-bars-in-bar-column-chart

There are a few suggestions of this here in UserVoice, but those seem too scenario-specific and I thought I'd just make a compilation of all of them here.

Even something as simple as just providing an additional object for each category that contains what points it has from each series.