I’ll give credit where it’s due, young Israel was and is extremely successful in holding the line and acting as a bulwark against conservative. Their policy of owning each shul and making a universal, mandatory, enforceable charter was very smart. I honestly don’t know where frum jewry would be without the work of young Israel throughout the years.
YI was not founded by modern orthodoxy, though most of its members and rabbis are such. That being said YI didn’t “produce” rabbonim – yeshivos did. They may have guided some young men and encouraged them to progress, but there is a limit if one’s entire Jewish experience is just young Israel.
Irving bunim was very close to Rav Aharon; he was a good man and Hashem rewarded his efforts by making young Israel a powerful force in the fight against conservative.
however the idea of sacrificing and ignoring flagrant violations of halacha in an effort to conserve…. Is not orthodox, it’s the very thing young Israel was set out to go against. True, emphasizing things like singing and socializing, kumsitzes, etc may not have been part of the European playbook, but they are not sacrifices.