I agree with much that you say, however, there are still 2 sexes... and as there are 2 sexes that are physically and genetically made differently then there will always be a difference to treatment...
For example... front line troops. It's the age old arguement, 'Not allowing women on the front line is sexist elitism of men...' Wrong! The main reason that women are not allowed on the front line is that men instantly react differently... it's nature, it's how we are! Men are instantly protective of females over other men. This means that in a fire fight a man, working off of instinct, without realising will do more to protect a female squad member than a male. This is dangerous in that environment as someone could be left to die as a squad member accidentally ignores him over a natural urge to tend to a female casualty first...
Now, that is an extreme example, and I know that it does not equate to online, however, it still has roots to your argument. I agree that there is some inexplicible behavior by people online, and some males (mostly young males) will defend women they don't know to embarrasing levels... but this is just instinctive of the male gender. Hormonal young men, who have just woken to the fact there are a fairer species with lumpy jumpers, will unfortunately do the first thing that comes into their head when confronted with one of these creatures[footnote] The language used in this section is in no way trying to be sexist... it is a perspective of a teenegers mind. Women are a new concept to an adolecent male. Also, I am in the military, and ethics and diversity are accepted, even when language appears to fail in this aspect![/footnote]... try for acceptance!
Unfortunately it will never go. It is a natural part of human emotion. You said you had a boyfreind... imagine if he treated everyone exactly the same... well... first of all he wouldn't treat you any different to his mates at work/school whatever, and you probably wouldn't have got together with you in the first place... infact that thing in his personality and demeanor that caused you to be attracted to him wouldn't have outwardly been shown, and you wouldn't have had the spark that set the relationship off!
Finally... as a perfect English gentleman, I can unfortunatly conclude that I, myself, do and will always treat males and females differently in a social environment...! I am mandated as a man to give up my seat on public transport to women, help with bags if they are struggling and open doors/pull out chairs for them! (All but the chairs thing I would do for blokes too, to be honest, but out of kindness and upbringing not societies norms...