Cultural, or for that matter any other form of "appropriation" is an obvious, and to a certain degree intended consequence of globalisation. It is unavoidable as we mix and experience each other's cultures.

When we create a meme or a parody, we are appropriating a scene or a clip of someone else's life. Are we appropriating that as well. Is that a bad thing?

Do all these SJWs really want to revert back to the days when there was very little if any cultural interrelationships? circa 1700's

As an afterthought, seems that this entire cultural appropriation malarky depends on someone being offended, be them the source, the memer or a bystander looking for an issue to yell about.
If the meme is flattering, does it still fall under this "crime".
e.g. a head of state honoring his host by donning a piece of traditional clothing or reciting a famous anecdote or saying from the host culture. This is a very old and revered form of diplomatic respect not only observed at head of state level but all the way down to husband meeting wife's family first time for e.g. How do SJW react to this?