Mainstream journals are complicit, but are not the biggest problem.
The biggest problem by far is modern society: Tenure, getting paid a livable wage as a researcher, not getting stack-ranked and eliminated from your organization all overindex on positive research results that are marketable. This "loss function" encourages scientific fraud of sorts.
When, in those mythical non-"modern" times, was it easy to get tenure or a livable wage as a researcher? How open were the doors to this and what proportion of society got a realistic chance to pursue such a career? More people getting a chance means more fierce competition.
The biggest problem by far is modern society: Tenure, getting paid a livable wage as a researcher, not getting stack-ranked and eliminated from your organization all overindex on positive research results that are marketable. This "loss function" encourages scientific fraud of sorts.