Because the standard says that it should. In this circumstance they can legitimately claim "in all good faith". We can't lambaste MS for running roughshod over standards when ever it suits them (and believe me, I do) then turn around and moan because we don't a like the side-effect of them implementing a standard correctly (correctness here being defined by the standard, not any other measure of desirability) - that would be somewhat hypercritical.
MS are (by my interpretation at any rate) being catty about this and using it as an excuse to get a petty shot out against Google, but that doesn't alter the three facts:
1. The standard has flaws
2. MS has implemented the standard (flaws and all, but that isn't the point)
3. Google (and others, though Google is the one MS are calling out) appear to be using a loophole in the standard to go against the spirit of the standard. If they don't agree with using that header for its intended purpose then they should just not include it. Including a header that is intended to be machine readable but giving it human readable content is not something that can be easily defended: they could easily include it as "x-P3P" instead which is perfectly valid. Any human that does looking for the P3P header will find a message in a x-P3P header just as readily and it wouldn't confuse the client application into opening greater access because it doesn't understand the "for humans" message
Perhaps, considering the "assume human fallibility over malicious intent unless there is evidence otherwise" maxim, Google (and facebook, and everyone else that does this but isn't being fingered for it right now) did this in all good faith rather than to deliberately make use of a loophole, in which case the right course of action is to encourage them to correct this oversight instead of telling MS to ignore part of the standard.
Because the standard says that it should. In this circumstance they can legitimately claim "in all good faith". We can't lambaste MS for running roughshod over standards when ever it suits them (and believe me, I do) then turn around and moan because we don't a like the side-effect of them implementing a standard correctly (correctness here being defined by the standard, not any other measure of desirability) - that would be somewhat hypercritical.
MS are (by my interpretation at any rate) being catty about this and using it as an excuse to get a petty shot out against Google, but that doesn't alter the three facts:
1. The standard has flaws
2. MS has implemented the standard (flaws and all, but that isn't the point)
3. Google (and others, though Google is the one MS are calling out) appear to be using a loophole in the standard to go against the spirit of the standard. If they don't agree with using that header for its intended purpose then they should just not include it. Including a header that is intended to be machine readable but giving it human readable content is not something that can be easily defended: they could easily include it as "x-P3P" instead which is perfectly valid. Any human that does looking for the P3P header will find a message in a x-P3P header just as readily and it wouldn't confuse the client application into opening greater access because it doesn't understand the "for humans" message
Perhaps, considering the "assume human fallibility over malicious intent unless there is evidence otherwise" maxim, Google (and facebook, and everyone else that does this but isn't being fingered for it right now) did this in all good faith rather than to deliberately make use of a loophole, in which case the right course of action is to encourage them to correct this oversight instead of telling MS to ignore part of the standard.