Here's the thing.
First some background. I was born in South Africa and lived under apartheid. I'm a brown person. I'm amply aware of white supremacy and hate it with every inch of my soul. However, I've also seen black supremacy and black nationalism. While white supremacy oppressed us, black supremacy burned down our town. And yeah, I've also seen brown/Islamic supremacy (my own group). Heck, even in the UK, I have Indian Muslim family I visit that gloats how they got together and drove the blacks out of the neighborhood because they bring drugs and prostitution.
I give all that as a background because if you live in any way long enough you quickly realize how every group has an 'alt-right'. This point cannot be overstated enough.
Now when white people were just so damn powerful as it was the 'norm,' yeah we could all just pretend only white people were racist. Or I guess in modern social justice terms... that only white racists matter because only whites have power.
This is some serious bull shit in my view, because all groups have power. I'm in Canada now. I'm Indian. My high school heavily Indian. Yeah, do you think white kids had any power? Nope, they got punked off for being white same as any other people.
This is the point we are in history and why the alt-right is more prevalent. Regular white people are seeing how society is allowing every other gang to arm itself and spread itself to the teeth, while singling our only white people.
Only white people can't be proud of their identity.
Black power... that's a good thing. Not for me. To use modern lingo. I get triggered by black power as rioting black people burned down my home in South Africa in the name of black power.
Indian power... that's a good thing because ethnic people need to have an identity. ...
women power... that's a good thing.. because...feminism.
These extremist groups really only gain power when regular people starting siding with them. I'm a bit of a realist. I don't pretend we can stamp out all form of hate, but various thing in regular society have people join their 'alt-right' movement and think they are legitimate.
Again I can speak from my own example. Muslim communities are segregationist and racist to any level. You can't be openly gay. Heck, it's really tough to have openly left Islam as I did. I'm still battling through it.
I really and truly don't see any different between white supremacists and muslim supremacists and black supremacists... hate is hate.
The danger we face is that we've empowered and encouraged and turned a blind eye to all the other supremacist groups out there. White people aren't really blind to this and what is natural but to be sympathetic to the people who even have your interest at heart.
Oh I see parallels all over the place. White people might not be part of the alt-right, but they sympathize. The same way most Muslims aren't part of ISIS or radical groups, but they do sympathize. You I attend regular family functions with regular Muslim people and I get to hear wonderful conversation like:
It's sad people got killed over cartoons, but they really shouldn't be speaking about Islam anyways.
I guarantee you there's some white people today going, I'm not for hate or white supremacy, but all I want is for my kids to have an identity they can be proud of or very legitimate issue X,Y,Z.
Basically, of course you're right the alt-right has always been there. The problem is you can't just take this approach to only white people. It's basic group tribal dynamics. And society has changed quite a lot. It's not the 1960s USA where no other group had power, but white people and no other group is filled with hate and a conquest to subjugate and segregate other people.
It's sad to see us a society not really demanding every other alt-right part of society be pushed to non-acceptance as well.
It's also sad that regular white people can't just have a regular white identity and be proud of it.