While this is undoubtedly true, I think you overstate your case with this story. Societal attitudes often change at a glacial pace, but sometimes (and not terribly rarely) they change at a lightning pace.
Same-sex marriage is an example, as are other gay-rights issues. Honestly, I think hardly anyone looks at same-sex marriage being approved in Greece and concludes that it just happened overnight with little explanation. I think people who are interested are pretty familiar with how it happened.
I think many people understand that the approval in Greece is part of a relatively rapid process that began in the mid-twentieth century (after having been interrupted by World War II).
I think people understand that we can thank secularization, the de-emphasis of the authoritarian nature of organized religion, and the sexual revolution. I think people also understand that we can thank the advocacy and strong activism of feminist and LGBTQ groups that are fighting hard and intentionally to change public attitudes.
I think people understand that activism has had tremendous success, and has tremendous potential in future for affecting change.
As a former member of Act Up and Queer Nation, I understand up close and personal how deliberate strategies and tactics can remarkably speed up societal change. I understand that we absolutely must continue doing so today.
So your message isn't something I'm really interested in hearing, to be perfectly honest. Yes, I know change can be very slow. But I also know from direct personal experience that it doesn't have to be.
I also understand that when people are suffering, it's morally imperative to work as hard as we can to force change.
And I know we can win!
Because I've been there, and I've done that. I've born witness even as I have been part of the change process.