Jared Taylor wrote the essential article on "diversity," and he did it in 1997.  His The Myth of Diversity at the American Renaissance website bears many rereadings, as refreshers.  But it's about 5,500 words, and sometimes you just want something that's short and punchy (not long and like scorched earth!).

For example, one friend routinely closes his emails with some quotes, including this one:

"Politicians like to say that diversity is our greatest strength. That is b.s. Diversity simply is. The core question is: How do we extract its assets while minimizing its liabilities?" - Ron Wakabayashi,  Los Angeles County Commission on Human Relations

And Thomas Sowell has unloaded on the subject several times, memorably.  Here something from him in 2016:

If there is any place in the Guinness Book of World Records for words repeated the most often, over the most years, without one speck of evidence, "diversity" should be a prime candidate.

Is diversity our strength? Or anybody's strength, anywhere in the world? Does Japan's homogeneous population cause the Japanese to suffer? Have the Balkans been blessed by their heterogeneity -- or does the very word "Balkanization" remind us of centuries of strife, bloodshed and unspeakable atrocities, extending into our own times?

...

It has not been our diversity, but our ability to overcome the problems inherent in diversity, and to act together as Americans, that has been our strength.

[Will Orlando Change Anything?, Townhall.com, June 14, 2016

I just noticed another dandy example, from a commenter to a post at Mark Steyn's website.  (One has to be a member of Steyn's club to comment there, but the whole world can read the comments.)

Someone named "Drew" wrote:

"Diversity" has never been a strength anywhere for anybody since the Tower of Babel. It dilutes a nation's resources, weakening it. For example, in a multicult city an over-stretched police force has to develop expertise in over a hundred variations of crime in 200 different languages. Crime invariably rises, and variants appear that were never a problem earlier e.g. pickpocketing is favored by one group, cyber-blackmail by another, phone dunning of seniors by another, female genital mutilation and "honor" killings etc. etc. Hospitals are over-burdened with people who have never contributed a penny of taxes and whose health care is paid for by other people's taxes i.e. X paying in, X + Y taking out. Ethnic restaurants do not compensate for this.

Emphasis added because that reminds me of a highlight among highlights in Douglas Murray's 2017 book The Strange Death of Europe: Immigration, Identity, Islam:

[W]hereas the benefits of mass immigration undoubtedly exist and everybody is made very aware of them, the disadvantages of importing huge numbers of people from another culture take a great deal of time to admit to.  In the meantime, the agreement seems to have been reached with the general public that it is not such a bad deal: if there is a bit more beheading and sexual assault than there used to be in Europe, then at least we also benefit from a much wider range of cuisines. [p. 57]

Drew went on to write:

Even the Left implicitly admits diversity weakens instead of strengthens by prescribing it solely for white countries - the most successful and decent nations on earth, never for more homogeneous failures like black countries in Africa, for China or for Mexico. No white Americans are encouraged to cross the Mexican border illegally going south, are they? The Left is surely not gifting their magical diversity "strengthening formula" to white founded countries, is it? They're applying a mislabeled product that weakens instead of strengthens to make them equally dysfunctional to 3rd world backward nations.

While on this subject, I'll point to a brief VDARE blog that I did several years ago: "The Problem Of Ethnic Diversity Is Insoluble" — Malaysia's Tunku Abdul Rahman In The 1960s.

Summing up, I say it's diversity-babble, and I say the hell with it.

So you know, in 1928, broccoli was newly introduced in the US by Italian immigrants. A New Yorker cartoon drawn by Carl Rose and captioned by E.B. White ("Charlotte's Web") used that line, and for some reason, caught on. pic.twitter.com/2mNzcu5nvr

— Nameless Cynic (@NamelessCynic) March 29, 2018