An exact Google search for "point of contacts" yields 2 million results, including sites like UNESCO and multiple universities and other academic sites. Is this a legitimate plural form of "point of contact"?
The guiding principle in this situation is that you pluralise the noun that is multiple. Hence the plural of 'King of England' is 'Kings of England', because there are multiple kings but only one England. With point of contact, if you have more than one, it is 'points' that you have multiples of, so the plural is points of contact. On top of this, in this use 'contact' is uncountable and cannot be plural.
Yet you found hits for point of contacts on Google. I had a quick look, and it seems that this and this is what is confusing the results - POCs and SPOCs; Single Points of Contact with capital letters, to name departments or forms, and these become Single Points of Contacts when there is more than one of them. For example, this one is a communications toolkit supporting a government's Point of Contacts, and this one is a list of Unesco Point of Contacts, though ironically enough it is a list of one.
I’m sorry to say that it does indeed entail that a the frequency with which the plural of ‘point of contact’ is written (and spoken) as ‘point of contacts) is sufficient for it to constitute legitimate usage. I write that holding my nose, but I have to accept the fact of ‘demolinguism’ (that at some point how the general public use the language determines its rules: grammarians follow the demos!
But there is a good ‘metagrammatical’ question here: in fact, there are two.
- Is English language usage determined by the sheer numbers of instances regardless of whether or not the instance is produced by a native speaker of English?
A significant proportion of the English used across the internet must surely be by non-native users. Certainly that is true of our ELU. It is likely that the UNESCO material includes much more non-native than native writers of English. Should we then discount UNESCO examples? Who should decide? As I say, an interesting question to which the answer is far from self evident.
- Should every native utterance of English, including those of the careless, the lazy and the ignorant (however you identify these!), should count equally in determining standard English usage.
My grumpy-old-man gut tells me to cry out “no, never!”. Surely it should be ‘points of contact’: In the same way, if we turn ‘contact’ into a virtual adjective, we have to say ‘contact points. But the logic of my commitment to the evolution of language by natural selection tells me I cannot object to millions: that’s how ‘demolinguism’ works.