Kent Anderson has published "Detours and Diversions—Do Open Access Publishers Face New Barriers?" in The Scholarly Kitchen.
Here's an excerpt:
Analyzing their [Altmetric's] Top 100 articles for 2016 (data available here), 70% of the Top 100 articles were published behind paywalls. Given the preponderance of paywalled journals, it may be tempting to interpret a 30% rate of non-paywalled articles in the data as an indication that OA journals are punching above their weight, as they comprise only 18% of papers currently, according the best available estimate. Drilling into the data, however, tells a different story. Fully 1/3 of the articles in the Top 100 categorized by Altmetric as OA come from Gold OA journals from for-profit publishers (mainly Elsevier and SpringerNature), which suggests that for-profit publishers’ promotional practices may benefit the prominence of the content they publish.