“If number two pencils are so popular, why are they still number two?”

No. 2 pencils are often required on standardized tests. The name “No. 2” refers to the graphite grading scale. A popular joke has been cited in print since at least 1998:
 
“If a number 2 pencil is the best, then why is it still number two?”
 
   
The PENCILS Blog
12/09/2011 in Pencil News /by Pencils.com Staff
What is a No. 2 Pencil?
When most people think pencils, the No. 2 pencil is the first thing that comes to mind. But what does the “2” on a No. 2 pencil actually mean? And what do all of the “B’s,” “H’s” and “HB’s” being thrown around mean, for that matter? Well, it all has to do with the HB graphite grading scale used to classify the pencil’s graphite core. How does it work, you ask? Let’s take a look.
 
A pencil’s location on the HB graphite grading scale depends on the hardness of its graphite core. The hardness of the graphite core is often marked on the pencil — look for a number (such as “2” “2-1/2” or “3”) — and the higher the number, the harder the writing core and the lighter the mark left on the paper. As the pencil core becomes softer (through the use of lower proportions of clay) it leaves a darker mark as it deposits more graphite material on the paper. Softer pencils will dull faster than harder leads and require more frequent sharpening.
 
Google Groups: alt.stupidity
lifes little questions
Bucketmouth
2/9/98
Bill or Elayne wrote:
>
> 1)  If a turtle lost its shell is it homeless or naked?
Homeless: Turtles almost always wear underpants.
> 2)  if a number 2 pencil is the best then why is it still number two?
Because the number one pencil is just *too* good to write with.
 
Google Groups: bit.listserv.tbi-support
Thoughts.. (jke)
Yaron Hillel, M.A.
2/19/98
(...)
10. If the No. 2 pencil is the most popular, why is it still no. 2?
     
Google Groups: comp.lang.c++
LOOKING FOR C++ DECOMPILER
BJdi339
10/4/98
(...)
Thoughts to ponder on:
 
If the number two pencil is so popular why is it still number two?
 
Google Books
The One Year Devos for Teens
By Susie Shellenberger
Wheaton, IL: Tyndale House
2002
Pg. 47:
If the Number Two pencil is really the most popular, why is it still number two?
   
Twitter   
ericanykol
‏@ericanykol
if the number two pencil is most popular,why’s it still number two????
3:09 PM - 24 Apr 2009
 
Twitter
Mary Palmieri Gai
‏@MaryPalmieriGai
if number two pencils are the best sellers then why are they still number two??
10:02 PM - 6 May 2009
 
Google Books
I Funny:
A Middle School Story
By James Patterson and Chris Grabenstein
New York, NY: Little, Brown and Company
2012
Pg. ?:
“If number two pencils are so popular, why are they still number two?”
 
Google Books
Housebreaking:
A Novel
By Dan Pope
New York, NY: Simon & Schuster
2015
Pg. 230:
If number two pencils are the most popular, why are they still number two?