Wise interview questions

I have spent around 6 weeks in the hiring process for Senior data scientist position in Estonia, starting from the screening interview, technical, case study ending with the hiring manager. I was waiting an offer, any answer, feedback or even showing any respect for me that they wasted my time, a big effort and time in the case study. Professionally, they must answer all candidates they have in their list either REJECTED or ACCEPTED and also give them a reason, it doesn't matter the reason is valid or not, JUST RESPECT. My intuition is that they had a data science task and they didn't know how to do it, so just put it in a hiring process and get the best solutions from the candidates without hiring.