Dear R’ Dovid
1: I am not an expert in hilchos Eruvin. I do not know what constitutes a halachic wall. Therefore I can not answer your question about Brooklyn and walls.
2: Whatever or wherever those halachic walls may be, R’ Dovid Feinstein does not believe they are valid, for whatever reason.
3: The populaton of Brooklyn, according to the US Census http://quickfacts.census.gov/qfd/states/36/36047.html was 2,556,598 in 2008 (I wouldnt be so quick to say “nowhere near 3 million”). What relevance the number 3,000,000 has to hilchos Eruvin, again, I dont know, apparantly you do. R’ Dovid Feinstein is obviously not bothered by this number as you are.
4: Someone copied and pasted all sorts of info from another site (I think it is still online here) that specifically addressed the questions you asked me. The answers meant nothing to me because the questions do not either. again, I do not know hilchos Eruvin.
5: Personally, I dont care “what is said” about anything. I only care about what my Rav says right now.
6: I am not trying to intimidate, impress or humor you with sarcasm. You can take what I said however you want.
7: I am NOT DEBATING YOU. Not in hilchos eruvin, not regarding the veracity of the things found in any sefer, not regarding the things said in the name of Rav Dovid Feinstein Shlita, not in the name of R” Moshe Z’l, nothing. Now that I wrote this, I realize that I am debating you in ONE thing. Your questions have been asked, someone posted answers to them, you just dont find them to be SATISFACTORY to your liking and the friends you quoted. I am NOT debating the merits of any answers.
8: If you believe that those who dont use the Eruv today are irrational, so be it.
EDITED