Am I the only one that finds this over the top?
"No 'subtle -isms' is about recognizing the ways we're unconciously [sic] making our friends' lives a little worse."
I'm sorry, if your life is made worse by a completely benign (and friendly) statement like "ok guys, have a nice weekend" then you are naive and irrational. Creating an environment that indulges every childish sensitivity does not do those individuals any favors and makes a mockery of their cause.
"For the last year, the 'No subtle -isms' rule has carried some implementation guidelines. One of these is asking people not to debate whether or not something is an -ism."
Accusing someone of (even subtle) sexism or racism is not to be taken lightly—this rule forces the accused to apologize (affirming the alleged bias) without defending or explaining themselves. This is unethical and dilutes legitimate complaints.
A proverb that comes to mind: "Those who speak most about misfortune will find it. Those who speak most about success will find it."