What problems, exactly? The author acknowledged cargo works but hand-waves over vague claims of "it does not track dependencies well or support arbitrary build graphs", followed by acknowledging those issues are either non-issues or solved problems whose solution was dismissed without any good reason (caching tools).
The author's claims boil down to "I wanted to shoehorn Bazel but had no good reason to, so I double-down on Bazel's only selling point while ignoring everything".
It's ok if anyone just wants to try stuff without having any rational or coherent argument to justify it, but let's not call that "problems".