Could you for example solve all the transportation problems in the world if the only vehicle was a automatic transmission toyota pickup (the old small ones not the newer full size)?
Why would you ever need something else?
Well not everyone can drive a stick, not everyone fits in a toyota (I am thinking height more than width). You cant carry the family. You cannot haul large objects, certainly not efficiently. How do you get the trucks to the dealer to sell? Drive them one at a time?
If we used a server class processor in our television remote control we would need an extension cord and a cooling fan, or would need to replace the batteries on every button press and wait for it to boot first.
Rtoses and operating systems, same answer as above. You dont use an rtos in a low powered microcontroller, not normally, you often have rom measured in hundreds of bytes and ram measured in tens of bytes. No room for bloatware. Purpose built software on purpose built hardware.
Look at the ARM vs Intel thing going on now, Intel is horrible at hardware design, their success is purely in conference rooms and telecons not in hardware on a motherboard. You can get the same performance using alternate instructions sets from alternate vendors at a fraction of the initial and operating cost. Why settle on one ancient solution?
Few operating systems are reliable, same with compilers and hardware for that matter. Some software and hardware is designed for performance or reliability but not necessarily for user friendliness. I dont want the landing gear lever to cause the pilot to have to reach over to a mouse and check the okay button on the "are you sure you want to deploy the landing gear window", and then watch the hourglass spin while it thinks about whether to do it or not.
For the same reason you need a pickup truck for some jobs and a tractor-trailer for others, you need one class of machine (and software) for home desktop, another for small-medium business servers and another for large corporations. You cannot just make a pickup smaller and infinitely bigger depending on the job, you need more wheels sometimes, enclosures or not, more or fewer seats, power takeoffs, hydraulics or not, etc depending on the task it is designed for.
Where would we be if we had stopped at the 8 bit processor running CP/M? It solves all the worlds problems why would ever need to develop an alternative? 100% of the innovations, cost savings, performance increases are the result of questioning the current solution and trying something different.
One size fits all fits no one well.
