Divide-and-conquer is one of the key strategies of kyriarchal* oppression.
I mean, this is really freaking obvious with the conflicts between subsets of "LGBT." A broad queer** coalition has more power to push for sweeping changes to laws and society, but it's easy to encourage people to turn on each other. The thing where laws protecting gay rights can be passed as long as the language protecting trans people is stripped out is just a means of getting the coalition to tear itself apart.
There definitely exist communities in which gay men, lesbians, bisexual people of both genders, transfolk of all persuasions, etc. all get along and co-exist (just like there are welcoming communities that span sexuality, race, religion, and other factors) but it's always the result of long, hard, painful work on the part of everyone involved and not any natural automatic solidarity.
*Please forgive me the word choice here, but it's specifically relevant to the point.
**Also maybe problematic? I 'm used to this word in an umbrella meaning but I don't know how contested a label it is.