Well, duh! Of course ingredients matter. The quality matters. It affects the nature and quality of the end result. This is always true but most acutely noticeable when the number of ingredients in a recipe amounts to a mere handful.
Take your basic loaf of bread, for instance, which has some flour, some liquid material, some raising agents, and not a lot else. The taste and texture of your bread will have rather a lot to do with the flour you use. Rocket science this ain’t (and I should know, I used to work for rocket scientists!). So, for a 100% wholewheat soda loaf, you would do very well to use a nice, coarsely milled soft wheat flour. For me that means Abbey Stoneground.