The point is that big companies with financial backing will use market advantage to stifle competition before it gets a chance (e.g. buying up the spectrum for cell phones, lobbying to prevent broadband competitors, patenting very basic concepts, buying up competition in its infancy).
You can argue they missed the boat on buying youtube and putting it to their own ends (e.g. YouTube prime is only comcast subscribers). It sounds like you want to disagree with me, but my two points are [and you haven't really provided arguments against either]
1. There is insufficient competition in the market (cell phones, ISP, computer parts, and many others). Much of this is due to deliberate actions by larger companies to protect their pie.
2. The consolidation of media is bad for consumers, and its death is good. The level playing field of a public internet made all the difference.