Should objects not recommended to lay flat on build-plate?

[CarterTG]

Some of the reasons are pointed out in this thread:

Trying to understand auto orientation's preferences

I don’t have the printer yet, but I am trying to understand some of the choices Preform makes. In these two PreForm screenshots, there’s the same part. The picture with the 45 degree tilt is what one-click print did. The other one was me just putting it flat to the build plate and then generating auto-supports. Clearly PreForm is doing what it’s doing for a reason. I just don’t understand what that reason is, which is why I’m asking here. [35%20PM][13%20PM]