I think that will result in 10000 questions asking how do I add an entry to a vector. There are a lot of dear internet do my thinking for me, and no way those people are thinking or researching before posting
The downside of disallowing ‘unworthy’ questions is that people feel made stupid for asking, and unwelcome. Also, people feel made stupid for answering, and unwelcome. There is plenty of elitism in tech, and you could keep the main stackoverflow for unique, well-asked questions, as well as adding the novice area.
The advantage of having a novice area of stackoverflow is that more people will use the site. While not every question will be great, the total number of great questions, and the total number of people helped, will be higher.
Turnover/churn. If a Q/A site allowed basic questions then the site would be flooded with them since the population of novices greatly exceeds sophomores or experts. Moderation would need to keep up with silo-ing these Qs into the 'novice area' you propose. Experts would need to sift more to get to the interesting, challenging or novel Qs if moderation can't keep up, which might affect the retention of these users, thus diminishing the resource pool available on the site.
To me it's clear that tact and grace is called for, and is currently mostly missing, when directing askers of basic Qs to existing answers, whether on- or off-site but there is such a thing as tragedy of the commons. Some stewardship and curation is required to maintain an acceptable SNR.
This is really excusing bad UI/UX (like surfacing existing answers while a user is typing a question) and a bad ranking algorithm. There is no such thing as "being flooded" only bad search algorithms, and bad UX. Google is "flooded" with a result set spanning the entire internet, and they manage to surface answers. Stack Overflow can do the same--they have more tools to rank and influence behavior (rewards, moderation, points) than google has because they control the site, its structure, and how it is gamified.
The only problem is if the question is not exact duplicate, but that doesn't happen very often with such easy questions.