You know, you might have shed some light on the core issue here. Usually for tangible goods, it is about choice, at an affordable cost. In the case of tech however, it is not about choice, but it is actually about access, at an affordable cost.
In theory, you could also just set up your own wireless mesh network to reach the internet. Its actually really simple: figure out the basic hardware, and then the software which goes with it, and then get the cooperation of your immediate neighborhood, and then the community at large, and don't centralize anything so you don't become branded as an ISP. Of course, the problem is that it is prohibitively expensive, at least in terms of time. So you might say "Well, it makes no sense. I will rather pay the very high price that my ISP charges". So you have just perpetuated the ISP's monopoly, because there is now one less person who has a good reason to potentially contribute to the wireless mesh network.
You can use Telegram instead of WhatsApp, but now you don't have access (because most of your friends are not going to move to Telegram just because you are such an amazing friend).
But here is the important thing: the fact that all these tech giants use every single dark UX pattern imaginable (to increase access on their products), and don't allow unfettered data export (to decrease access for competitors), means they are well aware of this and try to make access prohibitively expensive (again, in terms of time) if you chose one of their competitors.
I don't have a solution, but I think that is why the monopoly label makes sense.