John
Those serious about perpetrating fraud will no doubt use any weakness they can discover, if they have sufficient resources - but it is harder to fake a Rembrandt than to be Rembrandt.
Think about it. The modern way of doing history from obscure archives is equally, on your logic, a “temptation” for historians to invent archive sources knowing that few will be able check up on them. And that has been done, but historians still exist and we still trust those with sufficient credentials and reputation.
In the First Century it was easier: you could interview the same people the historian did, and in any case history was about public events. The claims about Jesus were known widely from the Day of Pentecost. As Paul said to King Agrippa after his arrest, “These things were not done in a corner.”
Of course, one can always construct conspiracy theories based on a plot amongst numerous authors to rewrite a body of history, but that is hyperskepticism. A least one of the gospel authors, Luke, has always been known not to be an eyewitness, and so would have been judged according to the standards of a secular historian from the start. Mark too is an unlikely choice for a pseudoepigraph since he is not even mentioned in the gospels.
Bear in mind that to write a convincing historical fraud takes an accomplished historian (Morton Smith’s highly convincing fraudulent Secret Mark comes to mind - it was only convincing because of his reputation as a reliable scholar.)
Furthermore, we have a large body of pseudoepigraphic gospels and epistles from relatively early periods, written either as pious fiction or as sectarian propaganda. These are clearly distinguishable by their a-historical features, as scholars have long known, and also by the very eminence of their supposed authors, compared to their non-acceptance by the early church.
It is the job of the historian to ask, “How did these documents arise?” It is, in contrast, the ideologically motivated who ask, “How were they faked?”