The article is a bit vague and hand-wavey (and the title is a bit off) but I would definitely say that Apple is hugely monopolistic, for a company sitting at #1.
Apple has a stranglehold on iOS browsers by forcing App Store browsers to use Safari's renderer and web view.
And being vertically integrated, the hardware and software are both locked-down in ways that restrict a consumer.
Why can't I install macOS on non-Apple hardware? Why do I need macOS to develop for Mac/iPhone? Why can't I replace the battery or install memory easily on my Macbook? Each of these are shady, manipulative business practices, and lo and behold, Apple has the greatest market cap (and least competitive pricing.)