It takes a lot of hard training to get the precision necessary to fly the demonstrations they do, safely, and at low altitudes. Safety of the audience. Plus the political ramifications if a crash did happen, remember the crash in Germany by the Italians. They may be normal aircraft, and are apart from smoke systems, and they are normal, albeit hight experienced, pilots flying normal manuevers. But they are flying them at abnormal altitudes and in abnormal formations.
Loops are normal.
It isn't normal to fly a loop in a diamond formation in close formation bottoming out a hundred feet or less off the ground. Which I've seen them do. It takes more than skill, it takes a lot of trust, and that trust takes time to develop. I deleted my copy by mistake.