The Reddit post from user work_account42 captures a sentiment we hear often: "I can see the use case for Lists, but nested arrays in a single cell, cool, but where's the practical payoff?" It's a fair question, and one that deserves a direct answer rather than a dismissal. We think the skepticism is healthy, but it also misses the deeper shift happening here. For context, consider how we've previously explored the limits of traditional workflows in pieces like Stop the Highlighting: Fixing Date Log Errors in Spreadsheet Workflows and Track your mortgage overpayments and see exactly how much interest you save. Those articles tackle specific friction points, date validation and financial tracking, that nested arrays can actually streamline in ways PowerQuery cannot.
The core objection is that loading a CSV into one cell with IMPORTFROMCSV feels like a party trick when you can just use PowerQuery to land the data in a proper table. That comparison is valid only if your goal is static analysis. But the practical power of nested arrays isn't about replacing PowerQuery for one-off imports. It's about enabling dynamic, formula-driven workflows that respond to changing data without manual refreshes or VBA scripts. Imagine a mortgage tracker where the underlying rate table updates from a live CSV source, and your calculations automatically adjust without a single PowerQuery refresh. Or a date-log error checker that pulls fresh logs into a cell and runs validation formulas against the nested array instantly. That's not a novelty; that's a workflow redesign.
The real use case emerges when you stop thinking of the spreadsheet as a static grid and start treating it as a computation engine that can hold and process structured data inline. The FLATTEN function is a bridge, not a destination. You flatten to extract, but you keep the nested array for operations that benefit from structure, like filtering across sub-arrays with HASALL or HASANY, or passing an entire dataset into a single LAMBDA without spilling across your sheet. For the user who needs to filter 5000 IDs outside their Power BI model, a nested array of those IDs inside a cell becomes a live, formula-accessible lookup table. That's not cool; it's efficient.
Our take is this: the practical value of nested arrays won't be obvious from a demo video. It becomes obvious when you hit a wall with PowerQuery's refresh latency or when you need a single formula to validate a changing dataset without breaking your layout. The specific takeaway here is to start small, try nesting a FILTER result inside a BYROW operation instead of flattening everything. That one pattern alone can eliminate intermediate helper columns and make your workbook both smaller and faster. The question isn't whether nested arrays are a gimmick. It's whether you're ready to reimagine what a cell can hold.