For example, it will benefit more people to secure Microsoft or Amazon services than it would be to secure a smaller, less corporate player in those same service ecosystems.

You could go on to argue that the second order effects of improving one service provider over another chooses who gets to play, but that is true whether you choose small or large businesses, so this argument devolves into “who are we to choose on behalf of others”.

Which then comes back to “we should secure what the market has chosen in order to provide the greatest benefit.”