Excuse me while I shoot your entire argument down with a volley of torpedoes because I'm a linguist and I know exactly what a symbol is. In order for something to classify as a symbol (in a linguistic sense, which is what we're talking about) it has to be recognised by an entirety of a given group, the group has to identify with it and it has to carry intrinsic meaning. The bald eagle is a symbol for Americans - it symbolises freedom - it soars through the air unrestricted, strength - it's a predator etc. The cross is a symbol for Christians - it symbolises Jesus' sacrifice, death for our sins, it's a symbol of absolution. Pepe the frog symbolises jack sh*t - it's being used because it looks funny. A symbol works very much like a sign - there's the signifier, the physical representation, and the signified, a mental idea. Pepe does not qualify as a symbol in any shape or form - it's a stupid picture. A mascot would be more appropriate, and even that is a stretch. For something to classify as a symbol it has to have the quality of symbolism which Pepe lacks because it's a stupid meme that doesn't mean anything.
As for "similarities" between people who consider themselves the alt right, turn that judgemental eye inward - you have a lot in common with a communist, but you are not a communist. It's a loose group of people with *similar* ideas, which doesn't mean that they're white supremacists, racists or bigots - some of them very well may be, others not so much. If you're going to put all of them into one "basket of deplorables", I might as well start calling you a commie - you share some of their beliefs after all, we might as well just generalise because the political scene has suddenly turned into a sandbox.
As to why I'm rising a stink over this, it's because a presidential candidate and his/her cohorts should spend exactly 0 seconds on addressing stupid Internet memes. This is an article that's supposed to support someone who might run the country, don't they have bigger things to worry about? Someone spent time writing that piece, then someone read it, approved it, they patted each other's backs, said "good job", posted it unironically and got paid. This is an article about an Internet joke written in earnest, that's the big deal.