While I agree with you, searching for unknown terms is easy, many people browse on their phones, where searching is not as convenient.
More importantly however, if a phrase is uncommon, then one person asking and one person answering can save hundreds of people from searching and thousands of people from not searching and not knowing.
A phone these days is even simpler than a desktop. A $20 Android phone can understand "Hey Google, what is ECC memory?".
HN is not like other sites. It is for informed discussion that adds depth to the topic. If I want a linkfarm of relevant topics, I can easily go to Google or Wikipedia. If I want to see karma whoring for copy+paste links, I can go to Reddit. HN is not going to stay more informative than other sites if we are satisfied with discussing basic topics.
More importantly however, if a phrase is uncommon, then one person asking and one person answering can save hundreds of people from searching and thousands of people from not searching and not knowing.