I think we're just disagreeing on different interpretations of the word effective.
If something works, but has so many negatives that you only use it when other negatives outweigh those, then it's effective in some sense of the word, but I'd maybe not phrase it as "the most effective treatment".
Kind of like pre-emeptive mastectomy for breast cancer, it's effective and it's the recommended treatment for people likely to have problems due to specific genetic factors, but saying "pre-emptive mastectomy is the most effective treatment for breast cancer" is missing a lot of important nuance and can sound extreme, even though it could be defended as a true statement.
If something works, but has so many negatives that you only use it when other negatives outweigh those, then it's effective in some sense of the word, but I'd maybe not phrase it as "the most effective treatment".
Kind of like pre-emeptive mastectomy for breast cancer, it's effective and it's the recommended treatment for people likely to have problems due to specific genetic factors, but saying "pre-emptive mastectomy is the most effective treatment for breast cancer" is missing a lot of important nuance and can sound extreme, even though it could be defended as a true statement.