I wouldn't call it obsolete. If you have console with firmware <4.0 you need to turn of gamecart port if you update. So no playing original carts anymore
I have the same ReiNX. I'm a bit affraid to try it without this option. First post shows version with this option but version 1.0.0 and 1.0.1 doesn't show it.
I have really strange issue. I folowed the guide, inserted payload (reinx.bin), and I see boot logo from reinx, then there is Nintendo Switch logo and .... black screen. I made backup nand and boot with hekate.
My Switch is 2.3.0. Could it be microsd card? (fat32 formated)