"If you allow your back office tech stack to dictate tech choices for your core products you'll have a company that can't compete or evolve."
I disagree. If you're like a lot of businesses, your back office tech staff know a lot more about the options than the people managing them. In turn, those technical managers know a lot more than any other department. Ask a financial person whether cloud is suitable for this deployment and all they can do is look at numbers provided by someone else. The tech staff and management should be able to tell you what cloud services they would use, what non-cloud alternatives exist, and eventually generate the numbers for the finance department. The people who generate those numbers are usually making the decision by the numbers they send, so you really need them to know what they're doing.
"Your back office is not unimportant and ppl shouldnt draw that conclusion simply because I say it shouldnt drive your tech choices. But efficiency gains should drive the cost and focus down over time for those support systems."
And depending on what "efficiency" means, that could kill your core service. Business people understand about long-term survival needs, where they will have to take lower profits for a while in order that they continue to have a revenue stream. They don't always go for that option, especially when they don't care about the long-term viability of the business, but they at least understand what it is. Efficiency which reduces quality is dangerous, and it is not difficult to explain this to someone else.