As the Summer Olympic Games end here Sunday in a final burst of spectacle, it is clear that the American-led boycott has done virtually nothing to discredit the Kremlin or raise popular doubts within the Soviet Union about the invasion of Afghanistan.

It is a view generally shared by tourists from the United States, West Germany, Japan and other boycotting nations, who came here because they like to watch games played at an international level. To this small but important group of people, the Olympiad has meaning and impact despite the boycott. The fact that premier U.S. athletes did not compete has been all but lost in the rush of sporting events, which appeal to spectators in part precisely because they appear apolitical, even at these Games.

One Chicagoan summarized this atitude clearly: "The Chicago Bears don't care if the other team's quarterback doesn't show up. They want to win the game and when they do, that's good enough."

Soviet citizens, inured for generations to making sacrifices at the hands of their leaders, have expressed only puzzlement or anger -- never self-doubt -- about the U.S. boycott.

Preparations for the Games meant fresh housing delays, food supply squeezes, and new waves of apprehension among the masses about foreign ideological "contamination," but in return, millions of Soviets have had whatever pleasure can be obtained from knowing that sports events involving athletes from 81 nations have taken place on the soil of the motherland.

This mystical patriotism may seem enexplicable to Westerners, but it is an important part of Soviet psychological reality. It is reinforced by the inability of most Soviets to form coherent views about the world outside their own closed borders because they do not have access to accurate information.

Under these conditions, the Kremlin has indisputably scored an internal victory by having been able to proceed with the Games. There is no evidence, after two days of random interviews with Soviets in the sporting crowds, individual citizens on their daily shopping rounds or with Moscow's shrunken group of political dissenters that President Carter's boycott has in any way achieved its intended purpose -- bringing home to ordinary Soviets the aggressive nature and international dangers posed by Moscow's intervention in Afghanistan.

Even at the sophisticated and largely cynical levels of young Communist Party cadres, many of whom have a greater access to facts than their less-privileged countrymen, the long accretion of Soviet attitudes has not been dented with self-doubt because of the boycott.

A young science researcher who joined the party several years ago because "it makes life easier," sat in a sun-filled neighborhood park several days ago, and voiced these views, which are representative of what many citizens feel:

"The Soviets didn't suffer from the boycott. It hasn't done anything bad to us. Our press is convinced that if Carter had not found the Afgan invasion as a pretense, he would have found some other reason to keep the American home."

In terms of the competitions themselves, it was not identifiably important to sports fans that only 36 nations won medals of any kind here, as compared to the 1976 Montreal Games when 41 won medals. That the Soviet Union has utterly dominated its own Olympiad, at latest count taking nearly a third of all medals, or 195, including an unprecedented 80 gold, seemed somewhat dimmed by the compelling drama of many of the events. The Soviets difficulties with the United States simply seemed unconnected to such episodes as the Coe-Ovett 800-and 1,500-meter duels, the world high jump records or the indomitable performance of an Ethiopian runner named Miruts Yifter.

The Soviets were counting on the impact of sports drama to defuse the politics of these Games, and at many points that is what happened. They aided themselves as well in this by carefully censoring virutally all signs of protest by the Western teams, some of which insisted on marching under Olympic flags and playing the Olympic hymn instead of their own national anthems. Whether participating nations intended so or not, Soviet manipulations made it seem to most Soviets and to much of the world as though no one objected to the Afghan invasion.

Despite thousands of essentially friendly tourists pouring through the city, the intimidating presence of more than 200,000 police and thousands more KGB agents never allowed for free contact between visitors and Soviets. The isolation was successfully reinforced by constant preaching from party agitators about spies and saboteurs posing as tourists.

However bizarre and unjust those warnings may seem to outsiders, they become real within this closed country -- part of the fabric of life that exists at an irrational but important level. A worker at a Moscow industrial institute related how one day last week an older woman became the sensation of the place with a tale of a friend who found a poisonous snake coiled in the refrigerator of the restaurant she manages. "Saboteurs put it there, no doubt," the young Muscovite reported the institute's sophisticated researchers agreeing.

Other city dwellers reported phone calls from provincial relatives during the Games begging them to leave Moscow to avoid "provocations" by foreigners. The Muscovites may smile at these homespun worries, but the fact is that there has been almost no contact with Westerners, even by Soviets who considered themselves both adventuresome and eager to learn about what lies abroad.

The same isolation has enveloped the few dissidents and Jewish activists who stubbornly decided to stay in town despite the flight of friends to avoid trouble and repeated demands or hints from the authorities that they leave. There have been no significant contacts with visiting Westerners, and even an open letter from exiled dissident leader Andrei Sakharov proposing an Afghan peace plan got short shrift from the Western press.

The real and pressing problems confronting Washington and Moscow will remain after Sunday. But the extinguishing of the Olympic flame will have no more impact on them than the lighting of it did two weeks ago.