BTW, if you read the above you will notice that I haven't used any "hindu" arguments to debunk.
Marriage and procreation are not mutually inclusive and can be exclusive. All marriage does is gives two people a chance to have a committed relationship with legal sanctity affording some protections.
When you say that, it reveals poor understanding of marriage and its role even from a western perspective, much less a "hindu" perspective.
IMHO, in the hindu tradition, the goals of life are crystallised as the 4 purusharthas - dharma, artha, kaama and moksha. Of these an individual's sexuality and sexual preferences are a small part of kaama itself, and therefore a very small part of the 4 purusharthas.
For the achievement of these purusharthas, one acquires the required capabilities as one progresses through life through baalya (infancy), youvana (youth), grishastha (family), vaanaprastha (retirement), sanyaasa (renunciation).
Man and woman have different abilities, but complementary roles in achieving these goals. Infants needs the protection offered by the family, youth need clear understanding of their own identity and sexuality in order to avoid the trap of getting fixated on sexuality alone and to be able to acquire the required knowledge and skills to move forward in life and play a productive role in the family (which offered them protection and an environment to flower) and the society (which offered his own family the protection and the environment to prosper). That is also why youvana is also called bramhacharya (celibacy) phase. This is not repression but prioritisation. Every life form follows it !
While gay attitudes are seen as a sexual proclivity that can be tolerated and accommodated, one can see that it gets and individual stuck in progressing to achieving all the purusharthas, since a gay couple cannot procreate by themselves. Human instinct to procreate is in fact the defense of mankind, and indeed procreation the definition of life itself. And while gay attitudes are accommodated, they cannot be overtly or implicitly encouraged, because when an invdividual realises that he/she cannot achieve the purusharthas by missing out on the stepping stone of the grishastha phase, then it will inevitably lead to despondency and leaves little motivation to pursue the remaining life goals. Thats why kaama which in the complete sense means desire and the seeking of pleasure in many forms, not just sex, and here on earth and not after death (then whats there to life for ?!!) is also a goal of life. Only its a transient goal (and not just because our capacity to procreate is also transient), required of course, but by no means the ultimate goal.
This is also why brahmachraya is not encouraged life long. Its a shortcut to bypass Grishasta ashrama, and gives up many forms of kaama, which makes sense only if one is resolutely focused on moksha and wishes to go straight to sanyaasa. No need for Vaanaprastha i.e. retirement when nothing has been accumulated to retire from, and there is no spouse to accompany you. This is not just extremely tough but is also not scalable. If everyone becomes a sanyasi, then who will put food into their bowls ?! Extinction guaranteed.
Each individual in the society is free to pursue the purusharthas according to one's own abilities and proclivities, and inevitably our abilities differ, and so do opportunities, and what we make of them ir our actions (karma).
The hindu society's goal ie samaaja dharma has always to let every individual pursue his purusharthas in such a way that a maximum number of persons are able to the farthest, thus assuring the not just the survival of mankind, but also realising its potential, by achieving harmony within self, in the family, in the community, in the environment, in the country and the entire world.
This is what Vasudhaiva Kutumbakam means, and kutumbakam means a family. A functioning, procreating, sustaining and liberating family in harmony within and without.
Deviations are inevitable and fine as long as they do not try to usurp dharma for themselves and try to make it the norm and compromise the purusharthats for the entire society.
There are many gnyanis on the forum much more learned and wiser than me. They will be doing me and us a favour if they can correct/add to the above.
Note to admins: Kindly move to appropriate thread.
Sorry BJP).