You can get a residence certificate from staying for 1 night in a hotel. They give you the TM30 and you head to immigration to get the certificate. Means nothing in reality.
There may be bullies on here (like any other Facebook group) but using an agent does cost. However you have to weigh up the fee they charge versus the direct cost to you of having 800k in a Thai bank giving you almost zero interest. It may work for you. It may work for others to use an agent.