I have found a lot less need to look up things like "are there optional parameters in .len()?" because the IDE helps with that.
I need to look up strange errors that I don't understand. (Like when you install a new library and your code breaks). Those are almost never in the official documentation because they didn't plan for it.
I was speaking partially from my experience and, as another poster put it, IDEs help considerably in areas of syntax usage.
Besides, with more stable languages (C++ has a 3 yr standardization cadence and new features are not covered well on SO) you can find in-depth answers on SO. Otherwise, many mailing lists (yes, they still exist) are a better source of more current and more detailed treatment of the topic than, "hey, how do I do X so that I can move on to my next thing at work."
Don't get me wrong, I love SO, but I feel it's more about, "how do I solve this problem now?" vs "I want to learn more about this topic." It's real value is in the comments that others contribute "around" the accepted answers.
I have found a lot less need to look up things like "are there optional parameters in .len()?" because the IDE helps with that.
I need to look up strange errors that I don't understand. (Like when you install a new library and your code breaks). Those are almost never in the official documentation because they didn't plan for it.