The main benefit of the ARM processor design was very high performance per watt which carved out a significant niche that then grew into a massive market
In the beginning, it had great power characteristics, but it was also much faster than any x86.
That it evolved in the direction of power efficiency is more an effect of it being power efficient and being popular with embedded manufacturers, which created a feedback look that guided it to extreme power efficiency with reasonable performance, while x86 went the route of performance, power be damned.
That it evolved in the direction of power efficiency is more an effect of it being power efficient and being popular with embedded manufacturers, which created a feedback look that guided it to extreme power efficiency with reasonable performance, while x86 went the route of performance, power be damned.