I get Amazon, and I've seen copies of the purported Bezos 'everyting must be a platform' missive, but when I joined the Google platforms group in 2006 and talked with Urs Hoezle about why all this infrastructure for search, we had a lot of interesting and far ranging discussions but he never said "Oh and we're going to rent this stuff out for money too!" Until the original AppEngine project, and that got a lot of push back and discussion inside Google about 'outside stuff' breaking out of the sandbox and into the Google infrastructure, providing outside access was generally viewed (in Urs' organization at least) as dangerous at best for very little value.

The Great Recession hit, Google stopped building infrastructure for a time and focused on utilization, which lead to some awesome improvements in cgroups and i/o scheduling and such, and only after that and some early successes of both AppEngine and other projects which were kind of like it but much less well publicized, did the idea start to be considered as something Google might actually productize.

I could completely see them building infrastructure at this stage which is purely for rent, they have the recipe for building data centers pretty well baked. But I have never heard it put that they started out with that in mind.