They were too early. Collaboration tools and business practices built around them matured only in the 2000-s, with video conferencing becoming widely available only in the 2010-s.

If you want to study the history of bureaucracy and business (an exciting topic!), it took about 20 years for companies to adapt their business processes to be typewriter-friendly. The key invention: short memos rather than long-form letters.

So yeah, my answer is that prior to the modern computer era, companies had a natural maximum limit on their complexity*size metric. This naturally limited the scope of world takeovers and made monopolies self-limiting in the long run.

These limits have now increased, and we're seeing companies taking advantage of that.

Some numbers: the largest unregulated (i.e. not AT&T) company in the pre-computer era was GM, peaking around 600k employees in the 80-s. Amazon has 1.5 million employees now. Walmart is about 2.1 million, Alphabet is at ~250k.

And these companies are not showing any signs of slowing their growth down.