What is the process and importance of submitting a TM30 in Thailand for foreign residents?

TM30

I'd like to share my experience from today, if it's nothing new feel free to delete:

I went to muang thon thani immigration office today because after sending my tm30 twice via post without receiving the receipt i decided to go in person and ask them about it. They asked me for the tracking number but i had not kept the receipt from the post office but the lady was so kind as to check in the computer. She said i did tm30 last year already and wouldn't have to do it again. But since the last time i had left the country and stayed in various hotels (longest for two weeks in quarantine) that should have submitted a tm30 which would require to submit a new one after returning to my apartment. By the way, prior to the submission via post i called the immigration hotline and asked for specific information about how to successfully do it per post and where to send it to but still didn't succeed.