As far as I understand, it's not that MIPS is the best at embedded, it's just that it's cheaper to sell as the license cost is non-existing and good support already exists in kernels and so on.
If MIPS offered adequate performance and features, good performance-per-watt, and a competitive licence fee, and if none of its competitors could beat it, doesn't that count as 'best'?
> it's not that MIPS is the best at embedded, it's just that it's cheaper to sell
That sounds a lot like MIPS being the best at embedded. Not high-end, sure, but a lot of embedded is "what is the cheapest processor that can run Linux?"