You don’t need to squat, bench and deadlift to gain muscle. These are simply movement patterns, of which there is a multitude of different variations to suit each and every individual. There are no golden rules when it comes to exercise selection for muscle gain. What works is the exercise that allows you to be most stable and generate the most amount of force, safely and under control. The only variable we then need to control for is progressive overload over time, making sure the session volume (sets x reps x load) increases over time.
When you begin your training, you will go through a detailed movement assessment designed to test not only your current capabilities but your mobility and working ranges. We then select the exercises based on this information, rather than shoe-horning you into an exercise you can’t complete.