It's good advice too.
Everyone enjoys doing the things they are good at. None of us like doing the things we're not good at. Problem is, if we never work on improving our weakest link, it will remain your weakest link.
I don't like hiza-guruma or ouchi-gari very much. They are two of my weakest Judo throws. But, I will occasionally work several minutes of those two throws, just to increase my repetitions and get more experience. As a result, my hiza sometimes comes from out of nowhere and works quite nicely in randori.
Sometimes I will let people work one bell (about 3 minutes) of their favorite throw, followed by another bell of their least favorite throw. As a coach it's my obligation to help people develop those weak links, which means I have to work mine as well.
Very true Kyle, it's easy/comfortable to work on what we are good at. For me, an example from basketball, my weakest link was my left hand. It took lots of work, but my left hand ball control skill got to be as good and on some techniques better than my right side. This of course made me more diverse and harder to defend because my offensive options skill set increased. In my experience from basketball, I know working your weakest link can turn it into one of your biggest assets. You just have to let go of your ego, be willing to look like a fool who doesn't know what they are doing on occasion and become friends with getting frustrated because eventually that frustration goes away and new skills crop up.