Does having too many noindex pages hurt SEO?

Can having a lot of noindex pages negatively affect SEO?

I run a community site similar to Reddit. Some discussions are useful and active, while others are low-quality. My current approach is to noindex any question or discussion that has fewer than 3 answers. Pages only become indexable once they reach that threshold. Very low-quality posts may also be deleted.

Now I am wondering if having a large number of noindex pages could be harmful for SEO. Would it be better to index everything, or is this approach reasonable?