I can definitely see that y'all would benefit from this close reason. It seems that you've shoehorned two close reasons into one and it's your second most-used close reason currently, accounting for almost a third of all closed questions in the last 90 days (requires 10k rep to view). For everyone's benefit, the current 90-day numbers look like this:
Reason Qty. %/total
unclear 779 32.30 %
stats/programming 739 30.64 %
duplicate 380 15.75 %
self-study 170 7.05 %
too broad 166 6.88 %
another site 88 3.65 %
other 25 1.04 %
opinion-based 23 0.95 %
datasets 12 0.50 %
Splitting this into two close reasons is an excellent idea as it allows you to give more guidance to users in each specific case. Helping users understand why their question is closed and guiding them to resources that may lead to the answer they need if the question is truly off topic or how to improve the question if it's not is an excellent thing.
We do generally recommend the format
Questions about X are off-topic because Y. For more information, see [Z](link to meta post).
As such, I suggest a rephrasing:
Questions asking for code review, or that are focused on programming, debugging, or routine use of statistical software are off topic. Programming questions with a reproducible example should be posted on StackOverflow.com. For help with particular software try the support links we maintain.
Questions asking for code review, or that are focused on programming, debugging, or routine use of statistical software are off topic. Programming questions [with a reproducible example](https://stackoverflow.com/help/mcve) should be posted on StackOverflow.com. For help with particular software try the [support links we maintain](https://stats.meta.stackexchange.com/q/793).
Fitting in "because Y" here isn't likely going to happen due to length but I'm not sure it's necessary in this case. You have a good amount of help available to users who have their questions closed with this reason.
So, considering this, you may wonder why I'm declining this request.
It's because of that last line item in the chart above. Half of one percent of closed questions on this site - 12 of them in the last 90 days - use that custom close reason. That's really not enough from our point of view to justify a fourth close reason.
That said, I wonder if you could rework your more generic "this isn't about statistics" close reason to include this somehow. I'm not sure what sorts of questions it tends to catch but it reads like the default "blatantly off topic" close reason
This question does not appear to be about statistics within the scope defined in the help center.
There's another close reason style that may be a better fit here. Here's an example of how it's being used on Life Hacks:
Does not seem to need a life hack — A "life hack" is a seemingly intractable problem that can be solved by thinking outside the box. Unfortunately, everyday "How to…" questions about learning a craft or new skill are outside the scope of this site. See about Lifehacks. If the author can show how this needs an "outside the box" solution, edit and 'flag' to reopen.
Y'all will be better able to judge whether that's possible but I could see something like this working:
Questions on Cross Validated should be about statistics, machine learning, data analysis, data mining, or data visualization but not about datasets. This question does not seem to meet our scope. These questions may be welcome on other sites, see the help center for more information.
This is a much broader close reason than the Lifehacks one, so it's difficult to make it perfectly line up ... but it really seems to be a catch-all. If there's a specific reason most of these questions are closed other than being blatantly off topic, that may be worth adding. There's 67 characters remaining and rewording could increase that count.
One last note, you might want to update your on topic page. It mentions that datasets are welcome on GIS in some cases but says nothing about Open Data! Don't forget to add it and link to their on topic page to make certain that anyone visiting can see what sorts of questions are in scope.