Consider the following three types of monopolies:

There are monopolies where a single entity has entrenched their position by having the categorically superior product, so far ahead of any competition and while no barriers are erected to prevent competitors, there simply is no hope and they will all play second fiddle. This type of monopoly doesn’t really exist, except for a transient moment, for if there initially wasn’t a barrier, there soon will be: as market leader, the monopolist accumulates capital that at best is unavailable to the competitors (ie zero sum resources, like land or labor), and at worst stands in the way of free competition (eg brand recognition, legally -recognized intellectual property).

The second type is the steady-state scenario following the first, which is a monopoly that benefits from or actively enforces barriers against their competitors. Intellectual property (eg Disney) can be viewed as akin to the conventional means of production (land, labor, capital), so the monopolist that controls the usable land or can hire the best labor will cement their position as monopolist. In economic terms, we could say that the cost to overturn the monopolist is very high, and so perhaps it’s economically reasonable to be a second-tier manufacturer rather than going up against the giant. The key ingredient for the monopolist is having that structure in place, to keep everyone else at bay.

The third type is the oddball, for it’s what we might call a “natural” or “practical” monopoly. While land, labor, and capital are indeed limited, what happens when it’s actually so limited that there’s basically only one? It’s a bit hard to conceptualize having just one plot of land (maybe an island?) or having just one Dollar, but consider a single person who has such specialized knowledge that she is the only such person in the world. Do we say she is a monopolist because she can command whatever price she wants for her labor? Is she a monopolist because she does not share her knowledge-capital? What if she physically can’t, for the knowledge is actually experience, honed over a lifetime? If it took her a lifetime to develop, then she may already lack the remaining lifetime to teach someone else for their lifetime.

I use this example to segue to the more-customary example of a natural monopoly: the local electricity distribution system, not to be confused with the electric grid at-large, which also includes long-distance power lines. The distinction is as follows: the big, long power lines can compete with each other, taking different routes over terrain, under water, or sometimes even partially conducting through the earth itself. But consider that at a local level, on a residential street, there can practically only be a single distributor circuit for the neighborhood.

I cannot be served by Provider X’s wires while Co-Op Y’s wires serve my neighbor, and Corpo Z’s wires serve the school down the road. Going back to the convention means of production, we could say there is only one plot of land available to run these distributor circuits. So at most one entity can own and operate those wires.

Laying all that background, let’s look at your titular question. For monopoly types 1 and 2, it’s entirely feasible to divide and collectivize those monopolies. But it’s the natural monopolies that are problematic: if you divide them up (let’s say geographically) and then collectivize them, there will still only ever be one “owner” of the distribution lines. You cannot have Collective A own a few meters of wire, and then Collective B owns a few meters in between, all while Collective C is connected at the end of the street. The movement of electric power is not amenable to such granular collectivization.

To that end, the practical result is the same no matter how you examine it: a natural monopoly is one which cannot feasibly be split up, even when there’s the will to do so. Generalizing quite a lot, capitalists would approach a natural monopoly with intent to exploit it for pure profit, while social democrats would seek to regulate natural monopolies (eg US State’s public utilities commissions), and democratic socialists would want to push for state ownership of all natural monopolies, while communists would seek the dissolution of the state and have the natural monopoly serve everyone “according to their need”. But the monopoly still exists in all these scenarios, for it can’t be done any other way.

Other natural monopolies exist, but even things like radio spectrum are relatively plentiful compared to local power lines, for which there really is just one place to build them. We don’t have wireless power yet.