Providing _places_ to publish the result is only part of the problem. The other part is incentivizing scientists to do so. And similarly, Nature itself is responding to incentives. The core problem is that scientists themselves, the individuals, do not mostly display much interest (in a revealed preference kind of way) for null results. If scientists were interested and wanted to read articles about null results, then either journals like Nature would do so, or the numerous examples of journals like yours that have come and gone over the years would have been more succesful and widespread.

Because of this revealed lack of interest, high tier journals don't tend to take of them (correctly responding to the lack of demand), and journals like your that specifically target these kinds of articles A) struggle to succeed and B) remain relatively "low impact", which means that the professional rewards to publishing in them are not very high, which means that the return on effort of publishing such a work is lower.

Don't get me wrong, the scientific community could do a lot more to combat this issue, but the core problem is that right now, the "market" is just following the incentives, and the incentives show that, despite what the stream of articles like this one over the past few decades is that most scientists don't seem to actually have an interest in reading null-result papers.