Having chase boats on hand reduces the chance of a bad situation getting worse. It will not prevent an accident to happen, but by providing quick relief it avoids the risk of additional injury happening.
Look at
how it's done in the Solent (UK). The dots are chase boats. They follow the competitors around to keep the race team informed of what's happening and to communicate to the competitors any change in the course (there was a shorten course in that particular event).
The sailing instructions however make clear that they are here eventually to help people but that they cannot be held responsible if they do not act. And if they act it's to save people and not boats. There is a huge disclaimer in the NOR:
Competitors participate in the regatta entirely at their own risk. See RRS 4, Decision to Race. Neither the organizing authority nor ISAF will accept any liability for material damage or personal injury or death sustained in conjunction with or prior to, during, or after the regatta.
And BTW, the people manning club chase boats in the UK have three certificates: At a minimum level 2 powerboat, first aid and
safety boat.
