Noone benefits from a label and who cares
Actually I disagree with this. I'm gay — to me, that label is actually very helpful and, personally speaking, I care about it quite a lot.
It is helpful when dating, or looking to date.
It means I can correct people when they make incorrect assumptions about who I am and who I'm likely to be attracted to.
It helps me access specific health services which are aimed at, and unique to, gay people. (And in certain circumstances legal services too.)
It helps me find other people who are like me, which is important socially and culturally as well as in regard to dating, sex or partnership.
It 'benefits' the blood donation people because they don't want my blood. (Don't love that one but it's another example of the term/label being used in a way that is deemed necessary by some organisations.)
For gay people, coming out is about stating that. Owning that label. Correcting the record. Even in a so-called ideal world, coming out will always be necessary to some degree because gay people are a minority. So the assumption of society will always gravitate towards straightness. Having a label like 'gay', 'lesbian' or 'bisexual' is helpful for this process too. It is helpful to stand behind being gay, or lesbian, or bisexual, and saying 'This is who I am.' It's clear.