From the market’s perspective it’s the ratio of units managed by each type that matters.

Hypothetically, if 1 company managed 1,000 units and 1,000 people managed 1 unit then that outlier owns 50% of the market while representing 0.1% of the land lords.

It would be interesting to see this breakdown in numbers. I would suspect there's some kind of power law at work, although probably not as extreme as the example you gave.

Also, keep in mind that on the flip side, landlords likely view tenants the same way - looking at aggregates and not individuals: "Yes, lots of people can't afford the rent, but as long as I can get enough to make a profit, who cares about the rest?"

Managing 1000 units is way beyond full-time job, for this you need staff, which is additional expense.