alt Hacker News> What "current results" are you referring to? No, people 50+ years ago weren't arguing that cliffs can lead to disincentives, they were arguing that the whole system is "socialism" and bad - something that has been repeatedly disproven.
In fact, we have disincentives like that because they were arguing that having a flat benefit for everyone would be socialism.
If you don't reduce benefit with income level, these disincentives vanishes and that's how all post-war systems worked in Europe (can't talk about the US) before the neoliberal crew started dismantling everything in the name of “reducing public spendings” for greater economic efficiency.
A benefit that doesn't reduce with income level would be universal basic income, which has many supporters in theory, but has never been implemented in practice so far, not even in the most socialist countries of the 20th century...