Even if you only have one client - do you really want to manually hunt down all profile-card instances and update the styling anytime you need to change the styling?

And if you had a bug related to profile-card styling, are you going to find all cards to update the styling? Are you sure you didn't forget some?

This approach seems to be based on the idea that design is completely immutable after the initial conception. This is... not how design usually works :)