Neville ChaimBerlin:
“You think it’s the right of any random CR poster to do that and use it as a basis to posken for himself differently than the posek hador?”
Are you for real? As GAON mentioned, Rav Henkin, Rav Zvi Pesach Frank, Rav Yonoson Stief, Rav Weissmandel and others, all disagreed with Rav Moshe at the time. They all relied on precedent. All current Manhattan rabbanim can rely on those rabbnim who disagreed with Rav Moshe. Moreover, no one is required to follow Rav Moshe even if he was the posek hador (as a matter of fact, many Chasiddim did not accept him as the posek hador, because he did not peruse precedent). Every rav big or small has a right and a duty to pasken as he sees fit.
Moreover, to begin with, this question is irrelevant as there are few non MO rabbanim living in Manhattan today.
“Even Gaon admitted that frum poskim haven’t come out in support of the eruv after Reb Moshe’s psak.”
This is simply untrue. Rav Moshe’s teshuvah was written and disseminated in 1952, and all those who are mentioned above signed onto the eruv in 1962.
“Also, the population of Manhattan has grown by a magnitude of 10 in the past century. How could it make sense to bring proofs from Rabbonim of the early 20th century?”
As some posters have mentioned your figures are simply incorrect. In any case, is there such a thing as a jumbo reshus harrabim? Of course not. Once an area contains a population of shishim ribo the debate begins. No one cares if the population is much larger.
“This is why I’m still posting on this thread. What issue do you guys have with just admitting that only MO people hold of the eruv? I thought I was pretty specific that when I referred to “common practice” I was excluding the Modern crowd.”
Why are you harping on Manhattan? Maybe because there are few non MO rabbanim residing there? Lets talk about the Brooklyn eruvin, Boro Park in particular, where the population is almost entirely non MO. Rav Moshe objected to this eruv as well, but many rabbanim allow carrying. So is following Rav Moshe common practice, or not? The rest of you comment is entirely out of line.