Sharing a live view of your spreadsheet without handing over the keys to edit is a problem worth solving, and the frustration in that question is entirely justified. Password protecting a file you update constantly is a workaround, not a workflow, and mirroring a single sheet to a separate file sounds like a clever idea until you start imagining the sync headaches. The real issue here is control: you need people to see the data, but you do not want them touching it, and that tension feels like a technical limitation when it should be a simple setting.
What this person is describing is a common scenario in any workplace where collaboration and data integrity pull in opposite directions. The good news is that modern spreadsheet tools, including the latest versions of Excel with Office 365, already offer the ability to share a read-only view of a specific sheet without exposing the rest of the workbook or allowing edits. Instead of building a fragile mirror system or relying on awkward password prompts, you can use built-in sharing options that let you set permissions to "view only" for individual sheets. This gives your colleagues the reference data they need while keeping the master file safe from accidental or intentional changes. It is not a workaround; it is the intended way to handle this.
The deeper takeaway is that the problem is not really about spreadsheets, it is about trust and workflow design. Password protecting a file or duplicating sheets adds friction and creates two versions of the truth, which is exactly what you are trying to avoid. A mirrored file can still be edited by someone who figures out where it came from, or it can break if the link between files fails. What you actually want is a single source of truth that everyone can see but only you can change. That is not a niche request; it is a core feature of collaborative data tools, and it should not require a workaround.
If you are using Office 365, you already have the capability to share a read-only link to a specific sheet, and you can set the permission to "can view" instead of "can edit." That solves the problem cleanly, without the awkwardness of passwords or the risk of broken mirrors. The next time you are tempted to duplicate data to keep it safe, stop and ask whether the tool already has a permission setting that does the job for you. In this case, it does, and the only thing left to do is use it.