Sodomy was a crime for hundreds of years before homosexuality was considered a mental illness. Or an identity. Before psychiatry existed. Mental illness was the "progressive" interpretation for homosexuality mid 20th century. It was actually used as a rationale for decriminalizing it in Britain and Canada in the late 60s.

What's the rationale for criminalizing pedophilia then? Yeah it harms others....so throw them in a mental hospital instead? The truth is we criminalize anything we dislike that we don't have an instant 'cure' for. We like to lock 'weird' people away and throw away the key. Even the sick or elderly we just dump in nursing homes

Add to this homosexuality is condemned by religion and there you have the jesus freaks going around proclaiming it was a great evil and NOT just a mental disease. I don't think it was ever the consensus that homosexuality was an uncontrollable mental problem. It went from being a pact with the devil to acceptance and in between you had a few decades of psychology being on shaky ground with the public