Of course there are exceptions, and there are surely cases where a first draft is excellent as-is and feedback will barely improve things. However, the chance that your thesis is such an exception is a lot smaller than the chance that you can benefit from feedback.

If mistakes or omissions are detected in a first draft, your supervisors can explain what's wrong and suggest improvements, if they are first spotted in the final work they will affect your grade. In fact, handling feedback well typically improves your grade too.

We see this tendency often. Usually because deadlines approach faster than anticipated, and/or students are reluctant to share incomplete work. This is a shame. First drafts don't need to be perfect, that's why they're first drafts.

In fact, this is precisely why you have supervisors. Use them. And remember, they are also the ones grading your thesis (or one of the people that do) so getting some insight into what they want to see is very valuable.