If I'm logging upvotes on a post or comments on a blog, which is about as serious as 99% of these b.s. startups are doing, I think it's fair to ignore errors.
I do agree that this should be pointed out in huge blinking letters though, or be a driver flag that is on by default. The amount of people who don't know this about Mongo, but are still using it to store gigs of data, is horrifying.
If I'm logging upvotes on a post or comments on a blog,
[...] I think it's fair to ignore errors.
Acceptable software, particularly in the class of databases, is obligated to tell you that it didn't complete your request. This is not an option.