I just don't understand some suggestions from this site

they always suggested to send a thank you note to employer after interview, that is really not necessary in my opinion. In my past >15 years career, i never sent any thank you note to those companies but still I got those offers. Why bother? if you are good enough, they will always look back for you. If you are too humble, they think you are just not confident enough for the job. Sometimes silence is stronger than speaking.

Just my personal feeling, do with your own judgement.