Is there a reason for this? Are games looked down upon if made with certain tools?
Simple answer - Yes.
A game should stand as a completed work, and not what toolset was used to create it...But in my experience, and it is a mindset of end users, who have opinions in general that if they know how it was made they box it into what they think its "value" is.
If a book (a) took 7 days to write and book (b) took 9 years - people assume the 9 year book is better. Its just the way it is.
By removing any info about the creation, allows the end product to represent itself in its completed state.
Of course sometimes it is beneficial to stress how it was made, as it becomes a great marketing venture with software creators etc.