Except that the "dumbed down" phone most likely has a whole lot more computing power than any of the big mainframes you might have used in college.
For those two do need it, you don't need a mainframe sitting in your basement like a furnace when a Rapsberry Pi has 500x the processing power of an IBM 4300 from the 1980s for a fraction of the price and size and power consumption.
There is absolutely no need to shit on the capabilities of modern smartphones when "arbitrary computation" devices are so cheap, small, and ubiquitous.