The grid system being bootstrap-based leads to cluttered markup
Currently, the grid system relies on using the bootstrap classes to arrange the grid. This leads to a number of wrapper divs for rows and columns, and global class names usage.
If you're trying to stick to semantic markup, you want to get rid of that clutter, and rather use the sass mixins directly for the grid. It also kinda violates the otherwise BEM-approach for components, because suddenly there's global layout affecting components positioning.