That's exactly the part that puzzles me too. I don't think anyone's under the illusion that discussing this topic on a football forum is going to lead to change, or that what we do or don't do about the world cup will instantly change attitudes there and elsewhere, but at the same time I think some underestimate the soft power these massive prestige sporting events like the world cup or the olympics can have.
I'm sure many people here have no bad intentions with their "don't like it, don't go", "how hard can it be to not kiss in public, or have separate hotel beds for a few weeks" or "their country their rules, your actions can't and shouldn't change other people' societies" but it misses the point. On the other hand I reckon some use these arguments knowingly or unknowingly as a way of hiding their true sentiment, that these human rights (LGBT specifically) are simply not a priority for them as it affects a fairly small percentage of society.
There have been a few who've argued people are being naive about even trying to change attitudes that are so engrained in some cultures, even going so far as saying try advocating for minority rights in the west 100 years ago and see where that would have gotten you. But how do people think attitudes changed back then? In some ways that also ignores how attitudes towards gay people have gone back and forth throughout history, even in muslim countries. Egypt for instance, probably one of the oldest societies if you want to argue this societal age/development timeline angle, had a fairly liberal attitude towards gay people in the 19th century until British occupation. So did Turkey under Ottoman rule, and they're still a fairly ok place for LGBT people although reportedly that's deteriorating.
People in the west fought hard against societal disdain, which isn't something that tiny minorities can easily do in autocratic/authoritarian countries. It took a while for that spark of change, but I believe some people lack the perspective regarding just how quickly things can change too. You don't have to go back 50 or a 100 years to see the changes in attitude in the West. Go back 5 or 10 years and you'll notice there's been a massive change in attitude in the general population even in such a short span of time. Islamophobia certainly exists and may play a part in some of the criticism, but I think that ignores the fact that rejection of homophobia and the topic thereof has gained massive traction in the past decade among Western countries and even in football, which is partially why the outrage is bigger than it would have been a few years ago.
So I really don't understand why people are arguing against criticism (if their general attitude is pro human rights), when that pushback is just as meaningless as me not going to the world cup for instance. Now that the world cup is undoubtedly happening in Qatar, it's unlikely that attitudes will change dramatically overnight, or at all. But there don't even have to be huge protest or activist demonstrations at the tournament for some form of effect. Even just showing that acceptance of minorities (in football of all places) is ok and normal can have a small but lasting effect, that may well sloowly evolve into incrementally more tolerance. Maybe it will not, but voicing your criticism of discrimination and showing support for the people affected surely cannot hurt, so why the pushback if that is something you'd generally agree with in a different context?