Short lived Observables and higher-order mapping operators

I was reading this article and I can’t wrap my head around why switchMap operator is preferred over other operatros like mergeMap, concatMap, exhaustMap in case of short-lived, finite value, Observables like HTTP Request?

import { of, delay, switchMap, mergeMap, concatMap, exhaustMap } from 'rxjs';

function simulateHttp(val: any, due: number) {
  return of(val).pipe(delay(due));
}


const saveUser$ = simulateHttp("User saved", 1000);

const httpResult$ = saveUser$.pipe(
  switchMap(sourceValue => {
      console.log(sourceValue);
      return simulateHttp("Data reloaded", 2000);
      }
   )
);

httpResult$.subscribe(
  console.log,
  console.error,
  () => console.log('Completed httpResult$')
);