HR short screen call, Then send me code assignment , i've sent code assignment but never respond to my work. i've sent again email just about please give me feedback but it seems no one is responsible for applicants

I had 7 interviews: 1 HR, 1 Hiring Manager, 1 Online ability test (inteligence + personality), 1 Online coding test, 1 On-site technical, 1 with CTO, 1 with CEO. I received positive feedback for all of them; after a 3 weeks wait for the final decision, they came back to me saying "we picked another candidate for the role". No reason why, no constructive feedback, nothing. A complete waste of time, especially that for the last part I felt completely left in the dark, I received no updates except for "your application is pending" checkpoints. I got told that they actually waited for the other candidate to finish all his interviews to make a decision. I get the feeling they don't want good engineers, they just want one man for one job.