They clearly don't think that, since right after they said:

Of course, due to substantial inequality between instance size, we expect to see a power distribution, with a spike on the left that quickly falls and tapers out. Power laws govern much of the real world; many phenomena behave according to this unequal distribution.

But look at that graph. Calling this distribution a power law would be generous to say the least. There is a massive spike corresponding to just a few instances, and the rest of the graph is nearly invisible to the naked eye, so tiny and so overshadowed by just a few giants. Frankly, this distribution is closer to the Dirac delta function than a power law.

All of your comments in this thread seem to have been a strong defence against perceived criticisms of the Fediverse, when the article isn't so much criticizing it as it's proposing that it needs additional safeguards (besides decentralization) to ensure it remains aligned with users' interests:

• Firstly by alleging that the author advocates everybody running their own instance

• Then by nitpicking that massive concentration in 3 instances has totally different implications to concentration in 1 instance

• And now alleging that the author only considers Fediverse successful if all instances are the same size.

These are really disingenuous and uncharitable ways to read the article. I'm sure the author has a perfectly good understanding of the concept of Federation, as they detailed several examples, and they have a lot of experience in highly technical computer science work.