not true at all! .177 is all you need for targets, the bullet travels alot faster, though not as far as a .22 however the accuracy of a .177 is better than that of a .22 you only need .22 for hunting
awful in which respect? Both are fine for hunting, shot placement is what counts, not which cal you use.
.177 is alot more forgiving than .22 due to its flatter trajectory, which makes it easier for people new to hunting to hit the sweet spot and kill their quarry.