Until a product is code, it is Communication. Product Communication exists in Conversation, Text, Visuals and Prototypes. All mediums have contextual value but Prototyping is the highest fidelity.
Product teams that don't prototype are simply operating with less bandwidth and likely missing out on crucial insights before investing in development.
Personally, I view prototyping as a rewarding part of the Design Process. As a Product Owner, this is the purest form of objective review. Does your vision stand up? Is your work thorough, thoughtful, beautiful and complete?
At the prototyping stage for a mobile product, I am a big fan of pairing Sketch with Flinto for the design-centered UX and richness of interactions and behaviors. For web products, I often pair Sketch with Invision for the organization and speed of execution.
Take a look at some prototypes that helped generate iterative designs, communicate product specs and/or solve arguments.