It depends, obviously. Prior art is easy to prove by pointing at an existing patent. It is also easy to prove by pointing at an article in a mainstream publication in the local language. So "protective publication" or "defensive disclosure" is a reasonable alternative to getting a patent (and perhaps letting it expire at the first opportunity).

Prior art is only difficult to prove if you're relying on something along the lines of folk knowledge among the indigenous peoples of the lands where the Jumblies live.

It's non-obviousness that is notoriously difficult to prove.

> Prior art doesn’t apply in foreign jurisdictions.

Can you elaborate on this? Japan, for example, requires you to disclose any prior art during application similar to the U.S. Israel recently adopted similar rules. These disclosures frequently include US and foreign (WO, EP, etc) patents and patent publications.

> A country that is first-to-file can file the patent then stop your domestic company from using the tech.

Assuming you filed first in your domestic country, then you just apply in the foreign country and claim priority from your domestic application - thereby granting your application an even earlier effective filing date.