Basically it's like advocating for old school paper encyclopedia in the age of Google.
I fail to see what is so inefficient with a web search as a second brain: the content is always up to date and you have a chance of stumbling upon something that is better than what would be stored in your second brain.
And let's not forget about that maintaining a second brain is a real time sink.
The only plus side of a local second brain is that it's functional without an internet connection, but can you really write software in good conditions without an internet access (I sure can't)?