A widely cited unofficial rule on the Internet is known as Godwin's Law . In it’s original form this rule states that “As an online discussion grows longer, the probability of a comparison involving Nazis or Hitler approaches one“. Mike Godwin noted that “overuse of Nazi and Hitler comparisons should be avoided, because it robs the valid comparisons of their impact“. The purpose of noting and publicising this is to reduce such false comparisons. It’s often used as a rule for conduct in various fora where it’s regarded that if you compare your opponent in a debate to Hitler or unjustly call them a Nazi then the debate is over and you have lost.
In more recent times due to successful application of Godwin’s Rule the frequency of inappropriate comparisons has dramatically decreased. This combined with the small number of people on the net who are interested in discussing historical events that happened ~60 years ago (and the even smaller number of people who are interested in learning about them) means that the possibility of robbing valid comparisons of their impact is small. Now a large part of the use of Godwin’s rule is because it’s regarded as an ad-hominem attack that distracts everyone from serious discussion more than most such attacks. To see examples of this you merely have to do a Google search for “Bill Gates” and “Hitler” (currently 597,000 web pages have both those terms).
Note that the original reason for avoiding such false comparisons is given to sustain the impact of legitimate comparisons. It is quite legitimate to use the term Nazi when describing anyone who wants to implement mass-murder and slavery on a national scale (or any of the other awful things that the Nazis did), or the propaganda and other mechanisms that the NSDAP used to gain power. It is also legitimate to make historical comparisons, comparing Stalin to Hitler is historically valid (both were awful tyrants that committed a similar range of crimes) – I’m not going to compare them in this post but I merely note that such a comparison is valid (and is the subject of much debate by people who are interested in history).
I’ve just had a religious zealot named Elder Dave accuse me of breaching some new version of Godwin’s Law. I believe that my mention of the fact that his religious group (which wants to deny homosexuals the same legal rights as all other people) has some beliefs in common with the Westboro Baptist Church  is valid. The Westboro Baptist Church seems to be the leading organisation in the English-speaking world for demanding legislation to discriminate against homosexuals. Anyone else who demands such legislation IS trying to achieve similar aims and should expect this to be noted by everyone who has any knowledge of what is happening in the world.
Religious groups are given a lot of freedom to discriminate internally (EG “Priest” is one of the few jobs that can be denied to a qualified woman without any legal recourse). Also I think that most people will agree that it’s acceptable for them to advocate self-repression (EG the book What Some of You Were ). But when they try and get legislation enacted to institutionalise such discrimination I believe that they are going too far.
As for why the 95% of us who aren’t gay should be bothered about this issue, there’s the famous poem by Martin Niemöller which is known by the line “First they came for the Jews”  (actually there are a few versions of the poem some of which don’t mention Jews – check the link for details). Here’s another Wikipedia link for the same poem .