The moat of all four of those companies is simply infrastructure, partnerships, and plain-old name recognition.

Data and iteration speed aren't moats. I don't know what you mean by "distribution".

In fact proprietary data IS a moat in certain circumstances. Example: German law, in order to create anything proper a lawyer NEEDS to read up specific commentary („Beck“) that requires a paid access and the data never was party of any LLM corpus since it only exists behind a paywall and otherwise is defended by lawyers. Therefore any german legal advice given from chatbots always (>80%) is flat out wrong even harmful at times if things would go to court.