Sony RX100 in a pros hands a d800 in a avg or beginners hands the pro will deliver better pics 
Could be said for high end cell phone to again content composition etc…
Same pro with phone or better camera better camera helps for sure
D800 junk kit lens won’t be so hot vs a lower camera with great glass
Mega zooms tend to suck why pros don’t use em but they are really handy for folks to not have to change glass so many pros have them for personal work knowing they are ok with less quality but convenience
Avg driver in a race car or street car will turn about the same lap time
Pro in race car or street will know how to push the race car
Same as a camera why I say unless your a pro or know why skip the dslr anymore
MP for sure 16MP phone does not match 16MP DSLR
22 caliber bullet ? CB cap vs .223 both 22 cal bullet but dif rounds for sure
D800 nice for some folks who want to printer over 40 inch but overkill in MP IMHO
When I did high end advertising work for Conde Naste travel and architectural digest or food & wine magazine most delivered files were under 16 MP and that is really high end work
Shooting in dark say dslr choices give me a Df or D4s over a d800 any day ! Lower MP but better
Going to the park with family nice small compact camera