People are constantly (and rightfully) on companies' asses talking about how they need to "give back to open source". Now you're telling me things are fine as-is. They're not.
If they want to give back to open source, they could use the money they're spending on seventy thousand t-shirts to sponsor projects or pay maintainers.
But it's still nice to get some recognition. And it would be a better play for DO. If they sent out 100000 t-shirts to those people who made the most accepted PRs over the last year, they'd hit a lot more longterm contributors and also get a better bang for their marketing buck.
