RFC 9309 section 2.2.1 says the rules of all matching user agent groups get combined, but isAllowed() picks just one group, so a user agent that matches several groups only gets one group's rules. my hunch is that the robots rules explain why answer pages never show up, but it's just a guess
on cost, it's worth checking whether the site query multiplier applies on the Live endpoint and comparing it against just appending quora