Exactly. Even for this small board, the IC has 0.65mm spacing of the LGA pads. It would be pretty difficult to assemble it without solder mask. Almost everyone

Exactly. Even for this small board, the IC has 0.65mm spacing of the LGA pads. It would be pretty difficult to assemble it without solder mask. Almost everyone who has the experience of etching a board, or even using a router to automate making one, and also has the experience of ordering a PCB, never makes one by hand again.