I'm not a pro but all our our kitchen and buffet cabinetry is the same in terms of look but it is two tone kitchen so there is more than one colour. We then have entirely different cabinets in each bathroom.

All the furniture and accessories in the house should blend and tell a consistent story. But they needn't and shouldn't "match". My kitchen cabinets and counter tops are not the same as those in the bathrooms, but they are in the same general style and fit the style of the house. Same with the furnishings and floorings. You should seek harmony, not matchy-matchy. Only exceptions are kids rooms. Within reason, they get whatever they pick out. Not worth a fight or battle.

I like simplicity. I'm a fan of keeping the kitchen, any adjacent open areas and laundry the same type. And doing something complementary to the bathrooms but using the same style in every bathroom unless its right next to the kitchen.

"...Should all cabinetry be the same?..."

Yes, of course. It's the simple and harmonious solution. That is, unless your architect or interior designer (or you, if you have an experienced design background), understand design and color harmony and recommend a different and considered approach.

The answer is, it depends...

All of the above answers are valid. In addition, factor in real-life cost issues. We have more expensive cabinets in our kitchen and adjoining mudroom and powder room. Different (but same style) cabinets in our master bath, and different (but same style) in the other bathrooms and in the laundry room.

It also depends on what look you're going for. If you're doing a vintage effect, sometimes even the kitchen cabinets might not match each other:

I wouldn't expect the other cabinets in either house to match.

No, cabinetry does not have to all be the same.

I used the same cabinets and hardware throughout my house, and only two different quartz countertops. We varied our tile selections in the bathrooms. I did have the cabinets in the laundry room painted pale blue instead of the dark stain I used everywhere else. I love how cohesive my home looks.

Generally I can appreciate two tone cabinets but generally I just think it takes a skilled architect or interior designer to pull it off tastefully. This a legit house on a mls listing in my area and I just think its awful. I'm counting four different finishes on these cabinets and its in a higher end home in our area!

I agree with you, Tamara. It's like they couldn't find enough of the same thing, so they used whatever was available.