Here are some thoughts regarding usage of addr:place (discussion specific to the UK). This tag is intended to be used instead of addr:street in cases where addresses are grouped together by something other than a street name. It is needed in part due to the rule that addr:street should always match up with a highway using the same name.
It is a problematic tag because mappers use it to represent slightly different things. Below are some of the ways I’ve seen it used (the addresses aren’t real, but are based on real examples):
addr:place=Midland Garden Centre [a business that hosts other separately operated businesses]
addr:place=Mulberry Court [a tower block without a street name]
addr:place=Elm Retail Park [a retail park without street names]
addr:place=Derwent Business Park [a business park that does not itself contain street names, but there is a parent street]
addr:place=Long Lane Industrial Estate [an industrial estate with street names]
addr:place=Westby [a village which does not have street names]
addr:place=Beeston [any village, town or suburb]
Opinions will inevitably vary on how right or wrong the different usages above are. I personally consider the last one (G) to be the most problematic. (B), (C) and maybe (F) most closely follow the usage recommended on the wiki.
The wiki includes a rule that an address should never contain addr:street and addr:place. This was only added recently and I certainly don’t think there is any reason to observe this just because the wiki says so, although I do recognise there is an ambiguity when both addr:street and addr:place are used. How should addr:housenumber and addr:unit match up with addr:place and addr:street? Should addr:place or addr:street appear first? Due to the ambiguity there is perhaps an argument for avoiding using both together, but this requires using other tags which only have limited recognition. Specially, where addr:street is used after addr:place, addr:parentstreet might be a better option. This tag is already needed to unambiguously map subsidiary/dependent streets with their parents. Where addr:place appears after addr:street, perhaps instead use addr:locality/addr:sublocality or some other similar tag.
It is better to avoid adding lots of new addr:* tags, but to fully add addresses in the UK, I think at a minimum we need addr:parentstreet and addr:locality (or other variants, such as addr:village, etc.). A tag for sub-localities, such as industrial estate names, would be useful too.
It would be helpful to have a wiki page for UK address containing examples of how to tag many of the more complicated addresses shown above. I have considered doing this myself in the past, but have realised more consensus is needed first.