Customer needs don't really matter in cases where monopolist (ab)uses the law to kill competition. That's the MAIN reason why monopolies are problematic.
The licensing deals that legitimized AMD's unlicensed clones came later.
See tangentially related topic from yesterday: https://news.ycombinator.com/item?id=46362927
Another approach was Transmeta where the target ISA was microcoded, therefore done in "software".
"Apple created a chip which is not an X86! Its awesome! And the best thing about it is ... it does TSO does like an X86! Isn't that great?"
I think the last time I ran amd64 on my mac was months ago, a game.
There's also the CFINV instruction (architectural, part of FEAT_FLAGM), which helps with emulating the x86-64 CMP instruction.