I think you majorly underestimate the "easily" part. You can make a pattern with your RNG, but once mixed it's pretty useless. Making one that can handle that is not in the slightest easy.

would only create a false sense of security.

You are assuming that your only adversary is the chip maker, but this type of RNG (if it were even possible to make it) would still be helpful in the other 99.99% of uses for randomness.