This is exactly the kind of problem that reveals the gap between what spreadsheets *can* do and what they *should* do. A user, frustrated after a long Google rabbit hole, simply needs a clean way to calculate the month difference between two dates to assign a membership renewal appeal number. The logic is straightforward: for a rolling seven-month window, the appeal number should reflect how many months out the expiration is from the current appeal date. Yet the solution in Power Query's M language is anything but straightforward. That's a failure of the tool, not the user.
What this user is describing is a core data-management task: transforming a date into a relative position. In SQL, it's a simple `DATEDIFF(mm, [Appeal Date], [Expiration Date])`. In DAX, it's similarly direct. But in M, the language Power Query uses, you are left stitching together `Date.Year` and `Date.Month` functions, multiplying years by twelve, subtracting, and hoping you didn't introduce an off-by-one error. The fact that a user has to consider building a helper table in Excel and loading it back into Power Query just to get a month difference is a sign that the tool's abstraction layer is incomplete. The user is not asking for something exotic. They are asking for a standard temporal calculation, one that any analyst would recognize as basic.
Our opinion is plain: Microsoft needs to give M a native `DateDiff` function, and the community should stop treating this omission as an acceptable quirk. The user's frustration is valid, and the workarounds, custom columns, helper tables, or switching to DAX, are all compromises that introduce fragility. For a platform that positions itself as the data-preparation layer for the modern enterprise, this is a gap that undermines its promise of accessibility. A tool that claims to empower users should not force them into a rabbit hole for a calculation that has been standard in SQL for decades.
The practical takeaway for anyone dealing with rolling date windows is to build a reusable custom function in M that handles the month difference, then store it as a query for future use. That workaround will save time, but it shouldn't be necessary. The real fix is for the product team to listen to the community and ship a function that matches the simplicity of the user's intent. Until then, every analyst who needs to map an expiration date to an appeal number will have to write more code than the problem deserves. That is a solvable problem, and it should be solved at the source, not passed back to the user.