Takeoff in mission on PX4

Hello everyone,
As I saw on the document, this link, in mission it is not possible for fixed wing to take off in mission mode, it should be either launched by hand or take off should be given first, then the mission should be activated. I got confuse, since I tried mission on simulation and it took off without an error. Also, to create a mission, take off waypoint is required as QGroundControl says. Could someone enlighten me about this? Also, is it okay to take off by rc first then switch to mission mode through rc also when considering that take off waypoint is required in mission planning. I really appreciate if someone can help, because I do not have any experience about missions on fixed wing.