all fetal genitalia are the same and are phenotypically female — praxis
Yes, that's the case, until the xx and xy chromosomes are activated and the pubic hump is differentiated into female or male body parts. The rest of the body is differentiated as well -- pelvic width, musculature, bone length, CNS, etc. This is true for mammalian development across the board (except for duckbilled platypuses (platypusi?). Nipples, likewise, again across the board. But men don't start lactating without a major hormonal push.
Men are men, women are women. East is east, west is west, and never the twain shall meet. (Kipling. Not a serious quote)
What have they given up — praxis
Might-have-been history is always fun to write, if unreliable.
"What was given up" probably won't be visible to younger gay people, let alone heterosexuals. Even old folks like myself are too young to remember some aspects of "gay liberation". But briefly:
forming gay all-male communities
outsider status
an alternative set of values
Stonewall, 1969, was not the beginning of gay liberation: It was a landmark that was latter mistaken for the beginning. Pieces of gay liberation had been happening for the previous 80 yers, here and there. Whitman's Calamus poems (1859) were about "the manly love of comrades"--eros, not agape or brotherly love. Gay men were around before then, of course, but mostly unacknowledged--which is what made it possible for them to exist (carefully) in plain sight.
Sex and companionship were a key part of the early gay community, and its forms could develop outside of the mainstream culture because, again, it was scarcely acknowledged. To the extent that gay men violated norms on sex roles, race, class, and age, the less visibility to the outside world, the better.
There were some high ideals in the Stonewall era too, but by the mid-1970s, gay activism was focused on opening the American military to gay men (Leonard Matlovich). Some of us never thought that that fight was worthwhile. BUT, high ideals had given way to across the board acceptance in everything from the military to marriage.
Outsider status is a valuable element, in that those who have it are free to develop a culture as they see fit. Join the mainstream, and that's no longer possible. Gay men developed a sexual culture of having many partners with less emphasis on long-term commitments. The mainstream objections to gay culture were about morals, and how promiscuity was immoral. Later (1980s) the health risks of unprotected promiscuity were highlighted, and true enough, there were avoidable risks. But the upshot was, "settle down with one partner", which is the heterosexual solution.
A major piece of public health effort was aimed at eliminated the locations where gay men met. Under cover of disease prevention, the key infrastructure of the gay male sexual community was lost.
Grindr has had a less liberatory benefit than one might think. By individualizing / privatizing the search for a suitable sexual partner, social settings like gay bars have been seriously diminished.
Marriage, children, and mortgages are a time-tested way of pacifying men. Once married, once having a mortgage, and maybe children, one takes on commitments that mean one had better comply, be compliant, else one may be fired, making the marriage/mortgage burden all that much heavier.