Most people are not conscious of the effects of friction on their decision process unless you needle them mercilessly to examine their decision process.
Having tests not be order dependent means that the tests are independent, which means if you delete test 3 then test 6 still works. Independence of tests affects your refactoring decisions. Splitting files, combining files, 2/3 conversions, 3/2 conversions, are all a metric pain in the ass if the tests are factored poorly. That means you keep limping along with other tech debt besides the tests.
Having tests not be order dependent means that the tests are independent, which means if you delete test 3 then test 6 still works. Independence of tests affects your refactoring decisions. Splitting files, combining files, 2/3 conversions, 3/2 conversions, are all a metric pain in the ass if the tests are factored poorly. That means you keep limping along with other tech debt besides the tests.