When I was reading the previous comments on Datadog bad habits when it comes to hiring process, I was thinking, hey they just had bad luck. I should have been wiser. This is probably more common than what you might think.
Here is my story, after getting a very prompt request to get on a phone interview asking for my availability, I provided my preferred times in their tool but got no answer. When pinging them back for lack of answer, a phone call was finally planned but the interviewer did not show up. We had to reschedule. Second time the interview took place and I was told they will come back to me shortly. Several weeks after without any sign from them I sent a mail to get news. No answer neither positive nor negative. Month later another mail. Still no answer. Abandoned. To be honest it was to the point that if I had received a positive answer I would have wondered if I should continue the process as some of my trust in the company processes had vanished.
I understand companies can’t answer to all the resumes they receive, but once they took you over the phone and told you they will get back to you, I think it would be the minimal politeness to do so. Even by mail, does not cost much.