Yes, I am sure of that. But own code is for programmers.
I don’t know how difficult it can be to implement it or if it would make posts processing slower.
But being able make variable substitution in posts is useful for users and admins.
For example, we have several posts were we inform our users about image uploading limits.
If we change them later, we will have to look for that posts and change them to reflect new limits.
If we can use variable substitution that would be done automatically.
There are more places were it can be useful: for example I have uploaded some images as custom resources of some components, to be used in badges and groups.
They have been assigned variable names, but I cannot use them in the badge page to refer them as icon images, I have to use the complete url.
If we change the resource we will have to edit each badge and group config. If we can use variables, it would be done automatically.
Being able to define some custom variables would be interesting too (in order to use them in posts an config pages).