THOSE WONDERFULLY incurable romantics -- the Nostalgia Buffs -- are at it again. Only this time, instead of simply sighing for the Great Depression or World War II, these happy folks are busy convincing the rest of us that we should at a minimum be wistful over, and probably longing for, the "smoke-filled rooms" of our political youth.

This nostalgia, which is laced with a heavy flavor of revisionism, recalls kindly the long time before the enactment of the Election Reform Act of 1974. In presidential campaigns of that period, there was no effective limit on what anyone could contribute to any candidate or, for that matter, on what any candidate could spend in any state or in any campaign. All of that was dramatically changed by the Election Reform Act. No individual citizen can legally contribute more than $1,000 (which is probably too low) to any presidential candidate. Severe limits on a candidate's state-by-state expenditures, as well as on the overall spending in pursuit of the presidential nomintion, were imposed by the campigan law under which both the 1976 and the 1980 campaigns have been conducted.

When the litany of the noxious "unanticipated consequences" of the campaign law is compiled -- the too-long campaigns, the full-time candidates, the devotion of more of the candidate's and the campaign's time to the raising of campaign funds (because the law forces candidates to raise just as much money only from more contributors in smaller amounts) -- fairness should demand that the campaign of 1968 be recalled as well and given something approaching equal time.

That year, the late Hubert Humphrey, trailing Richard Nixon badly according to the published polls, was forced to tin-cup it around the country to the point that he had to accept loans, rather than contributions, of $100,000 or more from 21 different individuals.

The Democratic presidential nominee as Mendicant was not an especially uplifting sight. The Fat Cat, the fellow who with one swipe of the checkbook and the pen could eliminate the campaign deficit, was still very big in American politics only three elections ago. In fact, only two elections ago, one man, W. Clement Stone, personally contributed over $2 million to Richard Nixon's reelection campaign.

One of the people who offered, through full-page newspaper advertisements, to assist Mr. Humphrey in 1968 was the General Motors heir and political activist, Stewart Mott. All that Mr. Mott asked of Mr. Humphrey was that Mr. Humphrey change his policy on Vietnam to conform more closely with the policy of Mr. Mott. It seems fair to say that if a similar offer were made to any presidential candidate on, say, trucking deregultion by the Teamsters on the Trucking Assocation, a formal national outrage would be declared. Mr. Humphrey never met the Mott standard in 1968, but it does seem reasonable to guess that Mr. Humphrey or his managers undoubtedly and promptly answered the phone calls of the 21 folks who had loaned the campaign one hundred big ones or more.

All of this came to mind this past week when independent presidential candidate John Anderson formally and publicly announced that the same Stewart Mott was no longer associated in any way with the Anderson campaign. This came after Mr. Mott wrote and circulated widely a 65-point memo on the campaign to Mr. Anderson. That's right: 65 points. Only graduates of the Evelyn Wood School finished the memo in the allotted time. But in earlier times, before the limitation on individual contributions in a presidential campaign, it would have been a pretty good bet that John Anderson or any other candidate would simply have swallowed hard and commented gravely on all 65 points. For Mr. Mott and Mr. Stone and all the other big contributors or lenders, the truth is this: the Election Reform Act of 1974 has made them almost obsolete -- and that's something to think about.