x86 has to scale from embedded boards to laptops to servers. AMD made different trade offs than Apple.
Apple chose to achieve a level of performance by keeping the frequency low and having a high IPC. High IPC means that cores consume a larger size of the die. That helped with lower power consumption.
x86 makers like AMD, did the other way around. They dedicated a smaller portion of the die to a core. That makes it cheaper. To make up for that, they used a higher frequency, which also means a higher power consumption.
Apple also has a node advantage, which also makes their CPUs more expensive.
AMD could totally do what Apple did: have faster IPC at lower power consumption if they would have release more expensive CPUs targeted at the mobile market.
But AMD and Apple have different goals.
If we stick to the mobile world, Qualcomm is doing with their Orion cores just what Apple did with their M cores. In the first half of this year we will see laptops with Orion cores that will have both strong IPC and low power consumption.