it is not cruel at all , as long as the dog has shade,cover,water,toys etc it is fine

my big girl (clover) stays out during the day weather permitting , and we dont have any troubles with that , she has a kennel with a doggy mat inside, she has plenty of water and plenty of toys, and is never alone for long.

if we are going to be gone all day during the winter and colder months or when it is hot she is left indoors (large sunroom) where she sleeps when its not to cold (if its cold she sleeps in my room,usualy on my bed)

oh and the little dogs we CANNOT leave outside because they bark ALOT lol