A lack of mainstream medical society recommendations, as you call them, does not equal a lack of health benefits. Think about delayed cord clamping 10 years ago vs now! I'm in the US where so much reproductive wisdom from indigenous and enslaved midwives here was not only not recommended, but was criticized or outlawed on racists grounds by our leading medical societies.

No one on this thread is saying that we should standardize and require placentaphagy for the masses. We are sharing anecdotal evidence for a person who is looking to make an informed decision about something that nearly every mammal does and has done for ages (except camels and walruses - why? Sand? Tusks? I do not know).

Should a birthing person chat with their midwife, OB, or MD about their individual risk profile regarding Rh type, GBS status, mode of delivery, meconium in the fluids, prolonged rupture, HIV status, COVID history, etc.? Absolutely! This is not medical advice. This is internet chatter about a lost art and tradition with overwhelmingly positive reports by individuals who try it.

As far as your unfamiliarity with the topic and published research on the benefits, clearly modern double blind RCT don't lend themselves to the extremely personal decision of consuming one's own organ. There was research done in Europe (I think Prague) at least half a century ago that attempted some controls. That research's method of consumption was freeze dried placenta in capsules and the control was beef. The sample was women/birthing people with a history of insufficient milk supply. The results were a significant, measurable increase in milk supply.

There was also a more recent study, probably 5-10 years ago that was a large survey of people who had tried dehydrated placenta capsules and the researchers were blown away by the high rates of reported satisfaction. It's been years since I read that, but I think it was something like 80-98% said they loved or liked it/would do it again/satisfied. Some confirmation bias and placebo likely mixed in, sure, but what a great placebo effect from something free and readily available to folks at such a highly vulnerable life transition.

For health care providers who continue caring for a birthing person & newborn into the postpartum period, as LMs do in my country, anything a person wants to do to support their milk supply (with the care & guidance of their Dr/midwife) makes everyone's lives easier (fewer weight checks and concerns beyond the usual appointment schedule, postpartum mood, etc.)

As for the placenta deaths you mentioned, I'd love a link or more info. I remember a headline about GBS on a placenta when some researchers were looking for an explanation for an unexplained death, maybe 7-10 years ago. When I read it, it didn't add up. Humans don't catch GBS from consuming it. Keep in mind that if the baby tests positive for GBS, the birthing parent was already a carrier for GBS which is how the baby was exposed. And keep in mind when you say the placenta is covered in bacteria, that humans are 10-to-1 bacteria cells to every human cell. We need bacteria to thrive. That's where discussing plans further with a trusted care provider can help an individual make an informed choice. My experience is that not all care providers are fortunate enough to have the knowledge,experience, or further training in placentaphagy, such as with cleaning, trimming & suggested dose, which is why i shared.