not using favourites is like someone saying build a building and you just building it like every other building, because you can and its not risky. obviously a team of your six favourites is unlikely to work, but making a team around favourites can make great teams that are less predictable than a vast majority of the metagame and improve team building skills. But what some people also forget it, it's funner that way
I never said to not use favourites. In fact I'm pretty sure a lot of competitive players have favourites that they build teams around, or will almost always include, although that is only when their preferred Pokémon is viable in the current metagame. Similarly in designing a huge complex structure you can definitely design it in a preferred form to give it creativity but the design must be plausible and you can't randomly design an ocean liner or 1000 metre tower without incorporating structural knowledge and the laws of physics.