It's evolution. Survival of the fittest, quite simply. The weakest are taken down, leaving more customers for the remaining, stronger competitors.

It's a rubbish example. The DNMs do not get better thanks to exit scams and takedowns. They get worse, as sensible and experienced administrators depart with a fortune, to be replaced by mendacious incompetents. Nor is the technical side of things any better - they have, if anything, regressed technically on the issue of multisig.