Ever heard of unconscious bias - if not I suggest you go find out, and perhaps test yourself (there are plenty of available tests on the web).
Why - is that one of your past times - testing yourself for unconscious bias? What do you find you are biased about? Or is that a requirement in the academic field - regularly check and identify your biases as part of your appraisal process?
My point being that someone who overtly engages in sexist, racist or homophobic comments (regardless of whether they perceive them as a joke or not) is very likely to also demonstrate unconscious bias against certain groups too. And that will manifest in all sorts of discriminatory practices regardless of whether that person thinks they are being discriminatory (or even wants to be).
I'm afraid your type of thinking should be consigned to the dustbin of history, and indeed increasingly is being in forward thinking organisations all over the place. Interesting you talk about the army and investment banking - an organisation and a sector that have appalling records in this regard - in the former bullying culture and lack of diversity that has been literally fatal, in the latter an old boy macho type culture that not only is detrimental on an equalities basis, but part of the 'culture' that was linked to the casino banking type activities that have produced so much pain over the past decade.
I have no idea about what you define as overt racism, sexism or homophobia - not that it matters on here as this all seems very subjective and seems to very much revolve around your personal tolerance levels on the issue. Feel free to consign my type of thinking to whatever dustbin you like - as a liberal I don't need you to believe what I believe - and if it makes you feel all warm inside to feel morally superior to me, knock yourself out. Glad to have been of service.
I didn't experience bullying or a lack of diversity in the army - I had a good laugh though. We were informed about rules and practices to deal with bullying so maybe these practices had worked in the areas I experienced, which is why I didn't experience any - only banter, jokes, camaraderie and lovely helpful people who would look out for me.
The middle office areas I worked in in banking did have some banter but also seemed quite diverse - some Asians, some black people, some gay people, quite a few women - lots of jokes aimed primarily at straight, white men but if they liked you and wanted to include you then they'd joke with you too. There were a couple of issues with mild bullying - I sorted my experience of sexism and bullying in a humorous way with an elaborate wind-up - in fact one of the VPs of the bank at my first job called me a "bastard" to my face while laughing as I roped him into the wind-up of the head of my team for mildly bullying me - the VP added that he used to feel sorry for me being the only girl on an all-male team but now he felt sorry for them. I was a bit shocked but it was a nice feeling when he called me a bastard. And I ended up being friends with the head of my team.
As we already established I probably would not want to adopt your world view on this issue and you clearly would not want to adopt mine.