Piwik now works on websites with 100M pageviews per month and more (much more) with the right setup
So to answer the original question: Nope, doesn't work.
(Quick test: if you're counting page views in millions per day, you're gonna have a tough time).
Piwik does scale to millions of pages per month. We've managed installs of Piwik at _1 billion_ pages per month that's 30 million per day! Don't believe what you read on Hacker News ;-)
How it handles that traffic? It would be great if they could share the architecture because using Mysql for analytics is not easy, you can't expect Mysql to handle concurrent queries that needs to aggregate billions of records when I visit the dashboard.
I know that GitLab use it, so hopefully one of the devs can pop up and say how it handles, but that's a vote of confidence in my book.
No, not usable in real life. Old-school PHP bloat that will slow down your site. Bonus: breaks occasionally on updates. Developers not willing to learn techniques needed for a quick logger with minimal impact. Run away from people using this with high traffic sites in a still-2005-PHP-mindset.