No, the point is that usually fitting things in RAM lowers the budget. So it's well worth doing proper analysis on whether or not you can (a) fit all your data in RAM and (b) if a cluster of machines does not become it's own reason for existence.

Replacing a large number of nodes with a single machine with a lot of RAM is usually a cost savings measure rather than a larger expense (and it saves power too!), and due to a lack of communications overhead and exploitation of the fact that you now have access to all the data in one go you may very well find that your algorithms run much faster.

A distributed solution should be a means of last resort.