Two things:
They were never "just for professionals" -- they were the "computer for the rest of us". Marketing wise at least.
They also were never about raw power. They were never the ultimate number crunching machines nor gaming laptops.
And the CEO of a company, executives, journalists, doctors, managers, etc -- people who don't need the latest Nvidia card or 32GB RAM -- are also professionals.
For videographers, musicians, illustrators, photographers, graphic designers, the MBPr 15" is one of the most popular, and well speced machines out there. Individual PC laptops can have this or that spec better, but rarely the all around package (weight, size, sturdiness, touchpad, screen quality, SSD speed, battery, etc) -- and in those rare cases, the price is very close.