Opteron had vastly better architecture than the Intel chipsets of the day, but it topped out at four or eight sockets, I forget.
IBM, at the time, could offer you Opteron-like architecture and performance, with up to 32 sockets, using Intel chips. That was worthwhile to some customers. "Intel" wasn't the selling position. It was x86 or x86-64, with "big" as the selling position.
I'm not here to apologize for Intel. I'm just saying, those IBM proprietary chipsets had their nice bits.
However, with custom glue logic, one could expand it very far - AMD offering in that space was "Horus" chipset which connected 4 sockets with external fabric (infiniband, iirc) to create 64 socket systems. Similar tactic was (and still is) offered by SGI in their UltraViolet systems which utilize the same principle using NUMAlink fabric and Xeon cpus.
Still their chipsets had neat features worth remembering, such as the ability to use local main memory as a last-level cache of memory read from remote nodes. And of course they went to 64 sockets which was respectable.