1) Bromances are based on mocking and rejecting queerness — The entire joke about the SethRogen-JamesFranco bromances of the world is that they’re parodies of queerness. Literally, the humor is about making queerness the butt of the joke (so to speak). It’s funny when straight dudebros enact any kind of queer attraction entirely because it’s something they wouldn’t actually do in any serious way. Queerness is the joke because who would actually want to be queer right?
2) Bromances are used to queerbait. Queerbaiting is when people (like writers of TV shows) throw in an undercurrent of queerness or use homoerotic tension for the sole purpose of keeping queer viewers interested. For example, on a lot of TV shows, bromances can be both a running joke (see #1 above) and also a constant hope. Queer viewers, who are so used to not having any kind of central representation in stories, are baited with bromances in order to keep them hopeful that the characters could be queer, but the result is that they never are because queerness is bad for capitalism. Queerbaiting is cruel and is a huge problem.
3) Bromances enforce white supremacy. Bro-ness seems to exist in a constant space of parodying and mocking otherness. Not only is queerness mocked and then passed off as humor; bromances are frequently about safeguarding whiteness by mocking people of color. Going back to Seth Rogen and James Franco again, time after time the humor of their on-screen bromances comes from racist jokes. From Pineapple Express (don’t even get me started) to the recent parody of Kanye’s Bound 2 video, Rogen and Franco’s bromance humor is literally predicated on either mocking race, or disregarding it and appropriating it for the white cis male gaze (think about how none of Kanye’s messages about racism in Yeezus seem to make it into Rogen and Franco’s parody video, or how Franco’s uncool white rapper trope appropriates blackness in order to make it the butt of the joke).
4) Bromances enforce cis male dominance. Okay this one isn’t that hard to see. Bromances are literally predicated on worshipping traditional masculinity: muscles, boys clubs, getting girls, etc. In fact, ladies are baited with bromances a little like queers: bromances are used to show ladies that dudebros have feelings and can be tender and care about friendship and loyalty, while also showing how they’re strong and masculine — all in order to get the girl. Where ladies are concerned, bromances literally act to shore up patriarchy.
5) Bromances are about asserting privilege. Finally, as kind of a summation of some above points, bromances are all about straight white cis dudes injecting their (irrelevant) opinions about queerness and race into mainstream discourse. Bromances literally have the privilege of being more talked about in magazines and interviews than queer issues do. Bromances allow dudebros to literally prioritize their own viewpoints about oppressed groups and pass them off as comedy or satire.
In conclusion, bromances are literally built on racism and homophobia by mocking othered identities for humor.
EDIT: wow I didn’t even go into “no homo” here it could practically have its own post