Not completely correct. You can have access to it without insider track. Just need Monthly (Targeted) channel and update to v1908 for Office 365....solely available for 365 insider
Note:
Dynamic array functions are currently a beta feature, and only available to a portion of Office Insiders at this time. We'll continue to optimize these features over the next several months. When they're ready, we'll release them to all Office Insiders, and Office 365 subscribers.