The placebo effect doesn’t help. It’s just noise in the data collection process. It’s particularly problematic with human trials that rely on subjective evidence. Humans have a bias that actions have effects, even when they don’t (gamblers blowing on dice, wishing on a star etc).

Any intervention will have people think that the outcome has changed because of the intervention. This doesn’t mean the placebo effect helped, it just altered the recorded outcome. If it was a device was used to make the measurement, rather than human opinion, we just call it noise/error.

It’s a common misconception that the placebo effect does something. It does nothing other than artificially increase subjective measurements. Placebo effect is stronger in very subjective medical conditions such as pain, shiny packaging and brand names are reported to provide greater pain relief. Such medicines are so tightly regulated the formulation and supply leaves very little opportunity for medicines to actually have an effect. You don’t see the same effect when it comes to reducing the size of cancer tumours or altering directly measurable quantities.

Doctors aren’t allowed to prescribe placebos in the UK. Because it’s dangerous and a source of corruption. Such as King Charles selling homeopathic services to the NHS. Doctors do recommend such services, they do this primarily to dismiss patients and their issues.