Thank you for the helpful summary. The Discouraged creative solution worked for me. I expect this will be a one off, if it is not I'll try and setup some ignored phrases.

I was trying to type the phrases "visible within O2's network" and "the O2 SIM card" but something is interpreting the company name as markup. I could type "visible within O2's network" but that seems a little odd. Is there a better solution for this off edge case?

Here are a few of the use cases for templates (as in {{math 2 + 2}} results in 4) that I can remember from the past.

No. You should list the (actual, real, day-to-day, not theoretical) things you want to be able to do that you currently can not, or which you do at significant time or complexity cost through cumbersome workarounds. Optionally, you might also say "in other cases, we currently use Wikimedia templates to solve these". Suggesting a solution is the least important part of a feature request.

I gave a trivial example as that is better than a complicated one. In a huge wiki, like Wikipedia templates are used for all kinds of things besides making links simpler.

T12511 is about a very different problem and use case. This request is about adding a feature that "will allow users to quickly create a wiki page with some specific base content.". T12511 is about adding a feature that lets users create a bit or markup that acts as a macro/function/template that generates a few lines of markup within a page.

I do not think this is a duplicate. T3963 is about creating template Wiki pages that start off ready populated with some basic data. This request is about creating a Macro like tag (which is part of the Templates feature in WikiMedia markup) not about creating pre-canned pages.