should science be an "open community" where ideas are exchanged and shared? how does NOT sharing information have an impact on scientific advancements?

Yes ideas should be exchanged and shared.

Explanation:

When informations are shared, their will be scientific progress and advancement in the society at large. but it is unfortunate that scientists have private incentives to avoid disclosing research.

When informations are shared by many scientists, they will test and build on each others works but the scientist refuse to share this because they may not be acknowledged for their work or they get scooped by a competitior.

Futhermore, Sharing information can catalyse new collaborations and also increase confidence in findings and generate goodwill among the scientists.

By not sharing informations, it will be hard for a new invention to be successful. Research is the activity that produces new product or better processes.