Walls and Ceilings - Taping all joints

I recently hired someone to drywall my kitchen. The day after he finished, cracks appeared along some of the joints. It turns out he only taped the joints with the tapered edges of the drywall and not the edges of the smaller pieces he had to cut out which did not have the tapered edge. The joints without tape cracked.

When I called him and asked why he didn’t tape all the joints, he told me you only need to tape the joints with the tapered edges and that if the walls are straight, which he said he thought mine were, the un-taped joints would not crack.

I have never heard of this and think this is total B.S. I have done some drywall in the past and have taped all the joints. I would like to hear from some you professionals out there and hear your opinion on this.

The guy I hired is coming back tomorrow to fix the cracks. I am going to have him make sure all the joints are taped.

Thanks.

hi
all joint must be tape no matter tapperd or regular
the have to make a bevel cut along the strait joint and then fill it with mud and tape over
and also no joint at corner of door frame
the joint must be in the middle of the door frame top

I have never heard of a pro not taping all joints!