[kevinmhickey]

I think their behavior matters more than their market share. As other commenters pointed out, defining market share of an infinite resource is not very useful.

These companies buy potential disruptors at inflated prices. Sometimes they shut the disruptor down to maintain the status quo; sometimes they guide the disruptor to create a new market. In either case, it creates a positive feedback mechanism that increases their influence and further entrenches the parent company in their customers' lives.

As a market (and governed society) we need to decide if this is something that we want or not. It may be too late for pure market pressure to stop this behavior, leaving it to regulators. Or we can decide it's acceptable and let it go for the benefit of the innovations that these companies create.

I don't know if monopoly is the right word for this, but it's something and it does matter.