It does not fully prevent and guarantee there won't be any breach but it is way more manageable if the critical aspect of the business is managed by the vendor who specializes in the subject. As we might have noticed, Roobet does also use Veriff for verification.
If we come back to the company choices whether they are willing to take an overhead cost for managing the data or outsourcing it. Do note that, KYC/AML management doesn't solely imply a simple thing like verifying whether the user is legitimate and matches the provided documents. There are many levels within this subject like fraud analysis and checking if one identity is not part of some blacklist or something. And it requires data whereas some companies who specialized in that kind of subject already have.
Let's check a third-party platform that Roobet use, Veriff and Seon. If you are going to their website, you can clearly see that they are solving many problems that are worth outsourcing if some companies are dealing with fraud or identity business requirements.