This type of slop main point is to see the downfall of the arrogant party, milk it well and it can rise up like a certain slop with shield.
Not necessarily and for many it's not true. It may be a cherry on top, but it won't make you full. A much more sustainable reasoning, "a cake for the cherry" you might say, is adventures and relationships, like with the Shield Hero and Raphtalia, and in this case with "the strongest duo".
"The rise of the shield hero" sucks precisely because it introduces over 9000 unnecessary shallow uninteresting characters, after a relatively short Shield Hero + Raphtalia adventure arc, instead of making it a cozy adventure story of a small cast of characters you like and care about.