ubiq: That’s like saying that shatnes is (was) a mitzvah that’s no longer observed since in America it wasn’t observed generally by Orthodox Jews in America until Joseph Rosenberger started Shatnes Labs and made a big campaign to have people observe it. They should’ve been observing it all along but weren’t.
In any event, your attribution to Reb Dovid is incorrect. He did not say that is Minhag Ashkenaz. And the poskim do not recommend not following Hilchos Yerusha strictly. They all agree ideally it should be followed. But they also recognize extenuating circumstances for many and resistance to following it by many of the hamon hoam, hence the heteirim to deviate from the correct Halacha if necessary.