I answer a bunch of accessibility questions everyday for testers and developers and more often than not, I do an internet search and find the most reliable, comprehensive and relevant answer across.
I will try to start adding those searched links here as blog posts along with the questions for my own future reference and in the hope that it will help others.
Q: Should we have alt text for background images?
A: the short answer is no. However, I found a more comprehensive and accurate answer here: Alternate text for background images, alt text accessibility (davidmacd.com)