Yes, I read the whole study a few days ago.
It’s somewhat interesting when empiricism vindicates over a century of rational argument and hypotheses proposed by various political theorists, and even anarchists and Marxists from over a century ago.
As the paper notes, there has been empirical support for this and other particular narratives in the past. I always found the Majoritarian Pluralism view to be really naive, and—if I may speculate a little—probably supported by the very elites who would prefer ordinary people to think they have a say in political matters.
I found the interpretation and analysis to be amusingly tentative, but that’s to be expected in a scientific paper that’s focused mostly on quantitative data. And there’s still that faux-naivety at the end about “democratic society” being “seriously threatened”—when the system was never really intended to be democratic in the first place.
The same institutional mechanisms that allow for oligarchs and business-oriented interest groups to dictate policy decisions exist in pretty much every representative system of government. I would speculate, I think plausibly, that similar results would be found in most other “democratic countries”.
The most depressing part isn’t even that ordinary people have no influence in policy making, but that they actually largely agree with the very elites who do (except for the business-oriented interest groups, where they surprisingly don’t correlate with anyone, while trade unions were the most representative of people—but unions are evil and undemocratic).
As @bolwerk touches on, and which is actually talked about a little in the study, I think there is a quite sophisticated system of propaganda which promotes elite and business interests, and ignores and marginalises views which would represent the interests of most ordinary working and poor people.
Think-tanks, business interest groups (unions for corporations), the corporate media, and the politicians which come from the political class, all more or less sing from the same ideological song sheet, and share similar values and interests. The political discourse is narrowed to a small range of allowable and thinkable ideas, and it’s these that prevail in the popular consciousness. I think it’s partly this why ordinary people with unremarkable wealth, and even poverty, will repeat the slogans, ideas and support policies which go against their interests.