I think not doing controlled crying is insanely cruel, based on my experiences with my children.
My wife decided to go down attachment parenting with our daughter. DD wouldn't go to sleep at night without her mum there, she would wake up and scream in the night until her mum came through and slept with her, which ended up being every night. If my wife didn't respond immediately, DD would scream and shout and become so distressed.
About 18 months, DW wanted to go out in the evenings. Initially I responded to DD in the same way, but after a while decided this wasn't healthy and decided to try controlled crying. DW went away for three nights, and I did controlled crying with DD.
It was hell, incredibly distressing for me and DD.
Then on the third night, DD went to bed and peacefully went to sleep.
When DW came back, she wasn't happy with me and continued with the attachment parenting. The difference between when she was there and when she was out for the evening was stark. When she was out, I could put DD to bed and she would go to sleep completely contented. She would sleep through and get a good nights sleep. She knew there was no point crying and screaming and getting herself wound up.
When DW was in the house, bedtimes continued to be a nightmare, with DD crying, screaming unless DW lay beside her. She would wake in the middle of the night knowing that if she screamed DW would would come and sleep next to her.
Controlled crying is hard, really hard and DW wasn't able to let DD cry at all. But having seen how it can transform a distressed child to a contented child, I think it is cruel to not try it.