> It's funny that you chose to use this analogy because most people improve old buildings by blowing them up and rebuilding everything

It's not funny, it's practical.

Even if we were to demolish and rebuild first there's cleanup. Then there is a survey. And then planning, input design and then after all that, construction.

If you were going to do all those tasks inside that building you already destroyed, it's now much harder to rebuild.

Order of operations matter.