To me, this is enabled by social media. This uproar against Eich wouldn't have been viral if it weren't for Twitter, Reddit, and others.
The people who complained used tactics akin to bullying: "do what I want (fire Brendan Eich), or else I'll make much noise as I can, and drag your brand through the mud".
The backlash was driven by self-righteousness ("my beliefs are superior to Eich's") and contempt ("his beliefs hurt people, so he isn't entitled to them"). These feelings are timeless and have been common throughout history. The problem is that it's easy for them to quickly spread on Twitter, and then get blown even further out of proportion, either by being mentioned on 24/7 TV channels, or, here, because of OKCupid pulling a marketing move by supporting the backlash.
And overall, the effect is that some opinions and subjects are sadly becoming taboo, and people have to be politically correct or risk having their lives ruined. This happened to Eich, it happened with Donglegate [1], and it will happen again. The common theme in these stories is social media.
[1]: http://arstechnica.com/staff/2013/03/donglegate-is-classic-o...
Causing indiscriminate collateral damage (and using various arguments to deflect blame onto your enemies) until people submit to your whims is a long and time-honored tradition (for example, terrorists).
Vicious attacks against those who (appear to be about to) "leave the fold" are also long and time-honored tradition (for example, apostasy in religious-ruled countries).
Given that They (the people doing the protesting) decided that Eich's political actions made him a "them", and that They considered Mozilla to be an "us", it was perfectly reasonable for Them to (1) attack Mozilla for associating with Eich, and (2) attack anyone associated with Eich until Eich was forced to submit to Them (in this case, to Go Away).
So no, the problem is that people decided to suddenly target one individual for protest over a years-old used-to-be-majority political opinion.