Hungry? The sink is leaking? Getting sued? It’s unlikely you’ll choose a restaurant, plumber or lawyer without first checking how many positive Google or Facebook reviews they each have. That applies to insurance agents too.
This might convince you to focus solely on a reviews-only strategy as the best way to grow and sustain your business. Bad idea. You’re missing out because both reviews and testimonials should be part of how you market your agency.
Reviews are collected by third parties like Google and Facebook. Testimonials are collected by a business. You shouldn’t focus on one at the expense of the other. Your search rankings, reputation and business growth are all based on how well you can manage collecting both.