I'm not defending this startup specifically. But, in general, I dislike this attitude because:
The first point is that it wastes everybody's time. This also applies when a recruiter letting us know the interview result. The recruiters love to make us feel like we are human. I actually feel the opposite.
When a recruiter wanted to let me know the interview result, they would send an email to schedule a call. Then, the call would have to happen in the next few days instead. This occurred during the time I was interviewing with 7 companies and trying to juggling deadlines and offers. Just fcking tell me the result.
Another point is that this kind of attitude doesn't account for "diversity" of preferences. I admit that different people would want prefer different things. But why do we default to the way that wastes the most time? Just send an email that I am fired and offer to schedule a time to talk. If I want to talk, I'll schedule the time.
Please don't see me as a "human resource". But, more importantly, please do NOT waste my time.
People are harassed for not tipping. People look down on you for not tipping. Even, for bad service, we still have to tip.