Technically it wasn’t the linker that’s simplified, it’s the loader.

Modern systems don’t worry about PIC code, they have virtual memory so everyone sees memory the same. The virtual memory system manages the relocation automatically.

OS/9 relies pretty much entirely on PIC code, that made the loader and multi-tasking easy.

Original MacOS also relied on PIC. For similar reasons, and it’s partly why code segments were limited to 32k.

Then you have things like the original 8086. As long as you stick with the “tiny”/“small” memory models, everything was relative to the segment registers, so code and data could be moved easily.

In contrast you had systems like the Apple IIGS. The 65816 does not support PIC well, so code segments carry a relocation table that allows the segment loader to relocate code during transfer from disk. The creation of segment and relocation table is the job of the linker.