The IBM had the motherboard on the left, along with the expansion cards, and the drives and power supply on the right. The AT continued this.
Clones wanted mostly compatible cases, and motherboards wanted to be mostly compatible with IBM cases and clone cases.
Then we had Amigas like the Amiga 3000, which had a similar layout but a riser to take horizontal expansion cards.
While some more bespoke PCs had vertical risers, most PC cases in the early to mid '90s were large. It was the machines we paid a bit more for that made being smaller in to something a bit premium.
While taking apart my Amiga 3000 is a bit of work, the design is absolutely wonderful, and more than once I thought about the design of it compared with later machines like the Sun Ultra 5, the Motorola StarMax (PowerPC Mac clone) and others.