Its the same reason some will fix they're own cars instead of using a mechanic. Some have the skill and patience while others don't. Some would rather just pay an agent rather than mess with it. I can understand that.
Look man, you have got to experience it first hand. That means a few trips to visit, explore and decide. Sure you can talk to people and get some ideas but it will be nothing like you have ever experienced before in real life. You will either love it or hate it, its a total lifestyle change. I have lived in or visited over 23 country's. Thailand still blows my mind and that's why I love it so. But we all have opinions, talk with experts on subject matter, you will thank me later.