I disagree, if you are just doing you won’t be learning new things. I work at a place where there a lot of of long-timers are there and at that time there were only people that can from different fields. Those people work since 10, 20 years without even mastering what they do.
If they have to do something new they either give up or just try to come up with something on their own. Most of the time people have done things like that before and you can just read about them or look at their code.
You're right! I'd say doing is important for actually understanding and retaining information while reading is important for understanding the triumphs and failures of others and "stealing" ideas.
Interspersing the two is perhaps the best way of learning. For example you don't want to learn to swim by watching 12, hour-long videos on swimming techniques, costumes and its history. You do wanna watch a 15 minute instructions video on how to get your feet wet and then go ahead and actually get your feet wet and then come back and watch the next 15 minutes of video on how to step into the pool.
If they have to do something new they either give up or just try to come up with something on their own. Most of the time people have done things like that before and you can just read about them or look at their code.