So much of our career path is decided on relations more so than deliverables, also self-promotion is key but it doesn't come naturally for everybody.
The idea that I shouldn't self-promote (because somehow it felt like bragging) and that people will notice if I do amazing work but stay silent was probably one of the most negatively impacting inhibitions I had at the beggining of my career. Also the book made me realize how 'utilitarian' and sometimes selfish I was in communication with others.
I had an amazing manager as a Junior who gifted me that book, it really gives you some perspective. We are often selfish listeners and are not committed to acknowledging the other in a 2 way relation. Once you condition yourself not to do that then building relations is way easier, and the space for self-promotion occurs naturally without a feeling of humblebrag.