Why do traditional roguelikes use a single tile for everything?

I've noticed that in most traditional roguelikes, everything is represented by a single tile, regardless of its size or importance. A massive dragon, a simple chair, and even the player character all occupy the same space.

I understand that this is a well-established convention, but I'm curious about the design philosophy behind it. Is it purely a limitation of early ASCII-based engines, or does it serve a deeper gameplay or readability purpose?

Would love to hear insights from experienced roguelike developers and enthusiasts!