Comment by snek

It's generally not a problem until the big companies start asking for features, asking for bugs to be fixed, etc., expecting anything more than what the maintainers choose to donate. If someone from Amazon reports a bug it's kind of scary, you feel like you've broken Amazon. You might even try to set aside time you weren't planning to set aside. It's hard to remember/enforce that you don't owe them that time (especially if they're nice).