Supposing that it really is impossible that a society can be neutral with respect to anything important - that it must either tend to support or suppress it - then this explains why things can move so swiftly from being forbidden to being compulsory.
If neutrality really is impossible, then to argue that something should not be subject to stigma is - in the long run - precisely equivalent to saying that it is desirable.
If neutrality really is impossible, to argue that 'x' is not evil, is the same as arguing that 'x' is good.
If neutrality really is impossible, then to argue that people should no longer be punished or suffer for doing 'y' is de facto to argue that they should be rewarded and feel good about doing 'y'.
If neutrality really is impossible, then when society ceases to persecute a group, it will always begin to privilege that group.
Of course, one might argue that it is not necessarily true that neutrality is impossible; one might argue that theoretically it is possible and desirable that society might maintain an attitude of impartiality with respect to important matters.
But looking back over the past fifty years, what does it look like to you?
To me it seems blazingly obvious that when society ceases to sanction a thing it always, always, always starts to honour that thing.