What benefit could competitors get from that information?

The strategic advantage, by definition, is something you, as a company, don't know what it is. If you know, then people leaving your company take the information to competition and the it's not strategic nor advantage anymore.

So, given that you don't know what makes your company better then the competition, it's better to hide everything you can so you don't accidentally disclose useful information. God forbid competition discover your own strategic advantage before you do.

A friend accidentally told me not just how many servers Google was deploying for Bard, but what they were putting in them and the volume of the scale up.

A competitor with that information might have made a rush on a supply-constrained component market or negotiated longer term pricing agreements.

It doesn't even have to be competitors their suppliers would love to know the total amount of widgets that they'll be buying. That way they know if they're the single supplier

It tells them exactly how much they have to invest in hardware buildout to stay competitive with Google in terms of raw compute.

This is right up there with being able to predict a competitor's total manufacturing capacity for the next year because you have hard numbers on their raw material purchase.

The ability to improve their data centers, of course. Google is the company that launched data centers with commodity components.