In my usage I meant to express that a modern system should be constructed similarly to how flexbox and grid determine the "display" property of the selected ele

In my usage I meant to express that a modern system should be constructed similarly to how flexbox and grid determine the "display" property of the selected element's children. If your code constantly requires manual display:inline-block; on elements (and it's not just to override the browser's default stylesheet), then you probably aren't adhering to a consistent pattern and your CSS's maintainability will eventually drop off at an exponential rate. Flexbox enables you to even avoid patterns like .inline-list>li{float:left;}, so sibling-level specificity isn't going to align with best practices anymore in the near future.