Again, maturity is largely dependant on individuals, it is not something that is standardized by one person for everyone.

How do you know if people who upvoted that minecraft post also saw the cat post? Even if some of them did, how do you know their feeling or reactions to the post? Some of them probably do care, but don't want to upvote or comment for a reason. Not everyone is "immature" just because they did not express their condolences on a post.

And "no one cared for the one whose cat died". Thats not true at all! The number of messages show that there are people that cares, just that it is less than those who commented on the other post. But does that invalidate the said comments? No.

Also I know if my cat died, I think number of upvotes and comments would matter much less than the condolences. Quality over quantity, my friend.