"Why did the mathematician work from…

A math riddle is:

Q: Why did the mathematician work from home?
A: Because he could only function in his domain.

The joke has been cited in print since at least 2012.

Twitter
Peter Friedman
@MrFriedmanMath
Why did the mathematician only work from home?? Check back later for the answer. #mathjokes
4:02 PM · Oct 16, 2012·Twitter for iPad

Twitter
psssssst malone
@redeyetreeefrog
Why did the mathematician work from home? Because he could only function in his domain
9:57 PM · Nov 7, 2012·Twitter Web Client

Twitter
cicadian rhythms
@Guderjahn1
Why did the mathematician work from home? She couldn’t function outside her domain
#Mr.Moodyjokes
@Llamajuice1 @NEDC7
8:05 PM · Dec 3, 2012·Twitter for iPhone

Twitter
Drake Akens
@DrakeQRandom
Why did the mathematician work from home? Because he can only function in his domain.
9:56 PM · Jan 16, 2014·Twitter Web Client

Daily Kos
New Day Cafe: Cool Crossed Puns…Part Two
The Marti for New Day Cafe
Tuesday April 09, 2019 · 9:30 AM EDT
(...)
28. WHY DID THE MATHEMATICIAN WORK FROM HOME?
Because he could only function in his domain.

Quora
What are some ridiculous puns?
Amit Kumar, Attended ISB. GMAT 750.
Answered Sep 6, 2020
Here are some good (meaning terrible) puns that I have collected over the years.
(...)
27. Why did the mathematician work from home?
Because he could only function in his domain.

Twitter
Lorraine Jo King
@lahlahbean
#sillysaturday
Why did the mathematician work from home? Because he could only function in his domain.
2:29 AM · Feb 22, 2020·Crowdfire App

“Why did the mathematician work from home?”/“Because he could only function in his domain.”