it is true if he's 2 separate tickets, which he said he has. So by using your thinking, you too are dumb. I replied as per his limited information. I based it on what is required for 2 separate tickets on 2 different airlines that are not linked as a through flight. You may know more facts about his flight than I do, for some reason, but that does not make my comments dumb.
It's not dumb. He didn't give the information required for knowing IF he had bags or not. Either way, a self transfer can require check in again and he therefore would need to go out through immigration ( ignore bag carousel) and go to departures for next flight. So my comment is correct. He needs to ask the airline. I've done both. Self transfer ( had to do immigration in BKK) and also transit with a through booking that didn't require recheck in.
it also depends on his ticket and if he needs to check in for his second flight. He may have to or he may not. Nothing to do with bags. It depends on his ticket.
he said it's self transfer. Which means he goes through immigration, collects bags, then heads to check in for next flight. So he's got to fill in the TDAC arrival card.
The website shows the type of ticket, duration, flight number and price. All that info is available on the airlines page. You see all that before you book! That's how people decide if it's the right flight for themselves. Go look. No point keep asking if you won't look.