In my experience, the only times you have to use the "css_element" and "xpath_element" selectors in Behat tests is when you have an accessibility bug (that the thing you want to interact with does not have a label, or the label is too ambiguous to be useful).

Moodle cares about accessibility. If there are accessibility bugs, we should fix them.

Therefore, I think we should ban the use of these selectors.

Starting with a complete ban right now is probably unrelalistic. Perhaps a softer way to start is by getting gherkinlint to warn about the. This can be done crudely with

  "no-restricted-patterns": ["on", {

      "Global": ["\"css_element\"", "\"xpath_element\""]

  }]

which gives

Running "gherkinlint" task

[HIDDEN]\report\log\tests\behat\filter_log.feature

  27    Step text: "I click on ".frog" "css_element"" matches restricted pattern "/"css_element"/i"    no-restricted-patterns

or if we wrote a custom rule, we could probably get a more developer-friendly error message.