People who reach the mentor's website, are looking for advice/counselling in regards to sensitive, private and important issues in their lives. Therefore, the potential clients want to be 100% sure that the mentor has the relevant credentials, experience, skills, beliefs and perhaps a specific methodology to give them what they need. showing credentials does not mean that you shouldn't 'showcase' success stories about clients - although you need to remember that in some cases (and even if the stories are anonymous), the fact that the mentor shares private stories publicly, very well might deter others from opening up and sharing their problems/challenges.
If you take clarity for example, most people review both my profile and my reviews before they decide to use my services, and only after they see that I have the credentials AND that I've successfully helped others, do they schedule a call.
I've successfully helped over 300 entrepreneurs, and I'd be happy to help you. Immediately after scheduling a call, please send me a message with any relevant information so that I can prepare in advance - thus giving you maximum value during the call.
Best of luck