Google has usage data that no-one else could get access to. It’s the usage data that improved the algorithms that led to more usage data - effectively setting up a natural monopoly.

By allowing their search algorithm to atrophy they have given up this moat to the point that others can breach it with LLMs that give similar results without the usage data.

And neither did the thousands of other companies that disappeared into obscurity.

Back in the 2000's, Google became the winner in search engines because they had a good product and gave better results. That was not a moat.

Then they expanded into an ecosystem, e.g. Gmail. That was a moat.

It would be if they were the only one with billions of dollars. Perhaps the nuance is that they have a moat but a rather small one with competitors that have credibly signaled that intend to cross it.

A barrier to entry is not a moat from the consumer <-> business standpoint.