Privacy, for one.
Google Analytics relies on a cookie controlled by Google, and is likely illegal under the European Union's GDPR. You are supposed to get consent from users before setting a third party cookie, which would require you to throw up a splash screen asking for consent (and just generally annoying visitors to your site).
By contrast, Plausible Analytics is a privacy-first analytics tool that does not use cookies, and respects user's privacy. Plausible is fully compliant with GDPR, CCPA, and PECR.
Effectiveness, for two.
Many people block third-party trackers via their browsers or browser plugins. But most of those lists don't include Plausible because it doesn't track individuals or use a third-party cookie. That means your stats will be more reliable than if you were using GA.
Speed, for three.
Plausible Analytics' system is fast and their script size is small, so it won't slow down your site.
As a bonus, Plausible also independent, self-funded, open-source, bootstrapped and debt-free. In other words, they are independent creators just like Outpost clients.
You can learn more about Plausible on their website. Just as a note, Outpost's group buying power means you get to use Plausible Analytics at a fraction of the cost you would pay on your own.
Go to the main documentation page. Or contact support@outpost.pub if you have questions.