Slack Frontend Engineer interview questions

I had the first phone interview with Slack. The guy was not very friendly and not helpful, I don't like his attitude. (He )He asked about my background and skills. The interview was nothing special, seemed like a phone screen but have no idea why I got rejected. The overall impression they gave me is that they are not really seriously to consider hiring new grad candidates. They schedule lots of interview for marketing but not really hiring so many people.