Hi there!
In my personal and professional opinion, either have a blog or you dont. If you have, you must destine the resources needed and be part of the strategy. Having a content site just for the sake of having it is useless and can tell users that you dont care and/or that you are lazy with other parts of your products/services.
There is no experiment (to my knowledge) that proves the need of a blog to rank well in the principal keywords.
Usually, blogs or content sites are a part in a big content strategy, where you can target other more semantic and/or answer questions about your products. I'd like to think it as you are creating a conversion funnel, where blog posts, content in other sites or any content is somewhat convincing users about your products/services.
Having a correctly structured content site (or blog) could help somehow through internal linking to express more clearly the anchor/keyword intent for some specific pages. Also, always consider that if you can attract users a little interested in some of your products, you are getting a share of visibility that you didnt have without the content site.
Hope it helps.
Best luck.
GR
