To answer all your questions in one point,
As the saying goes, 'hate the sin, not the sinner," often times people mistake peoples opinion on rehit as judgemental, when in fact it is just stating fact. For example, it is fact that Sarbloh Bibek is a mandatory rehit, thus when I make this statement, it will no doubt hurt those who don't not keep this rehit. However, this does not mean that one is targeting indiviuals, rather, it is an attack against a Sin, that being not keeping bibek. The same goes for Bana. Bana is also a mandatory rehit of Guru Sahibs if one wants to reach bramgyan. Seeing a Singh (unless forced to) not wear Bana is thus dissapointing. This does NOT MEAN that they look down upon the individual who doesn't wear bana, but seeing a Singh do dhil in rehit is sad. Once again, hating the Sin, of not keeping Bana, and not the individual himself.
This can be the same for anything. If you see an individual not do nitnem, you can state that he/she is not following Guru Sahib's hukam. Is this statement wrong? This is simply stating fact. The problem becomes when people make this the focus of their life, and purposefully look for weaknesses of others, and call them lower then thenselves or discuss these issues to an extent where it becomes the focus of their lives.
ਸਤਿਗੁਰਬਚਨਕਮਾਵਣੇਸਚਾਏਹੁਵੀਚਾਰੁ॥