This is a popular myth. Measles impairs the immune system memory so many kids die of an opportunistic secondary infection plus there is measles induced encephalitis that results in death or brain damage.
I had classmates that were deaf from the measles and I worked in the crib ward of the state hospital and about half of the residents were brain damaged by measles induced encephalitis.
A vaccine that protects you from one thing can make you more vulnerable to another.