The "broken comb" is a metaphor used to describe the next evolution of the T shaped designer. Maybe you'd call me a Tim Brown Fan Boy, but I think the T shaped designer is still the trump card. Here is where I think the Broken Comb fails:
The Broken Comb is a challenge to go deeper into different fields of expertise, which on the face, looks aspirational. My immediate response to that aspiration is: Jack of all trades, master of none. We live in an age that exposes less than exceptional work, and I'd argue that exceptional developers are rarely exceptional designers, and exceptional designers are rarely exceptional business analysts, etc.
To be exceptional at anything requires extraordinary effort and attention. That's not to say that developers aren't good designers, but the Broken Comb suggest that you can be exceptional at several aspects of product development while building a successful business.
While I believe we all can get better (go deeper) at various aspects of our profession, I don't believe this is a substitute for building a strong team – one that makes up for the areas you lack in.
This is where the Broken Comb fails the hardest. There is no substitute for a diverse and skilled team. The Broken Comb metaphor props up the individual as a unicorn or rockstar team member, which I see as toxic – not only to the team but also to the product itself.
If you're going to put effort into something outside of your tangible tasks, I'd recommend putting more effort into what it takes to build trust, collaboration and respect among your teammates. After all, the magic in Design Thinking isn't locked away exclusively in having empathy towards other fields of expertise, it shares equal space with a diverse intake of ideas and opinions, which only come from other people.