Probably because they play the same game as Mark Zuckerberg, the Chinese, to some degree OpenAI... They all release open-weights models.

They'll generate some hype for their company that way, so it's advertising. They build good will. They undercut the competition. Or make it clear how they outperform them. Maybe they get some more investor money if they do expand to the local models market. I bet there's a million reason why it makes sense from a business perspective.

It's called commoditizing your complements. It's a complex strategy which Google has done before with Android and Chrome. They're masters at it.

These gemma models are small enough to run on your laptop or phone. They'll be bundling them with phones and Chromebooks anyway.

Might as well get some goodwill and let the horses run free before someone extracts them from the edge device anyway.

It can give them some plausible deniability if they just ship them off as tech-previews. I'm thinking for when that taking kitty app starts feeding into your delusions and telling you to hurt people.

A lot has been said, but to add to the list I'd say it gives them access to quite a large pool of free testers.

LLM architectures and optimization techniques change rapidly and by releasing open-weight models a lot of enthusiasts will evaluate new models for free, help implement support in inference engines, catch bugs etc. (and in turn, ofc, get a new model to run for free, so it's at least somewhat symbiotic).

We have at least seen this quite obviously when Alibaba released Qwen3-Next, which was a somewhat undertrained but still useful model which introduced the architecture that their latest models now use "in production" (also their paid "Max" models).

Random suspicion: It is correlated to how much compute US have. That's the only reason I can think of. I also wondered why they would do that when US tech are grabbing the global hardware. They'd like to keep control of inference in the cloud but are missing power thus lack compute. But they also benefit from a western AI ecosystem that have much more compute available. Pure guess, but maybe something like that ?

Cause no one really cares about them and Google doesn't want to fade into obscurity in this AI race.

Marketing

https://youtu.be/sXgZhGzqPmU?si=hrVq2gd9BqcU2YBS this guy explains it from different angles