What this should likely tell you, is that you are missing information and have an incomplete picture of the situation.
Or it could be MSFT just likes to spend extra money for no reason because they are simply stupid. I'm gonna go with the former though.
I'd be interested in all these behind the meter setups for large 24x7 loads that are being built using solar+battery though. I haven't heard of one personally, but I must be lacking information on the subject since you seem so certain these are common?