A lot of people will say "oh, it's ok - I spend lots of time with my single bunny"
But...most people are at work for 8 hours and asleep for 8 hours (ish)
That's maximum 8 hours left to spend with bunny, so s/he is alone for 16
Remember that most people also have to eat, wash, travel, do housework, bit of socialising, go shopping, other errands....and they're unlikely to have more than 4 solid hours left for their bunny....so s/he is alone 20 hours. Not so much fun for the bunny.