Goldman Sachs Developer interview questions

I was attending the 2017 SHPE conference so I was invited to apply for an engineering role with Goldman prior to the conference so that I may be interviewed once I got there. I was sent a HackRank test which was pretty easy so was scheduled a 45 minute interview. Once I got to the conference, I was interviewed and was asked medium to easy difficulty questions in the interview. I enjoyed my interview at this point and was beginning to consider a role with Goldman. Once I left the interview, I was emailed by the recruiter that the engineers liked me and would like me to come back to chat with a few more engineers. And that if I was unable to come back same day, I could just meet and chat with them at a Hospitality Suite (which is a relaxed casual environment held in the evening). Thinking that this was just something casual, I decided I could just go back same day to the interview booths and chat. Once I got back, I chatted with one engineer who seemed interested in me and what my interests in Goldman would be. Good chat. Then he suggested I meet another engineer. The other engineer came in and asked if I wanted to do any technical questions. At this point I was thinking this was supposed to be just a casual "get to know me" type thing, but couldn't hurt to do a couple technical problems for fun? He began asking me pretty difficult problems out of the blue, and I was struggling to come up with clean answers on the spot. I had no idea this was going to be part of the "chat." He basically ended up "technically interviewing" me for over an hour! I suppose because I couldn't do well in his idea of a casual chat, he suggested to the others not to move forward with me. I just felt like I got screwed over on the spot because I could have easily decided not to return same day, casually chatted at the hospitality suite, and prepared adequately for a real technical interview later on. It was totally spontaneous and wasn't ready to give it my best shot after a long day of conference and other interviews. A recruiter called me about a week later telling me they decided not to move forward with me but if I wanted to reconsider roles with Goldman in the future to reach out. I thanked her for her time and she seemed a little taken back that I didn't ask any follow-up questions. I don't think I'll ever consider a role there in the future and will employ my friends the same because of this weird process that had me go through.