My Ford Focus makes a crunchin noise when turnin.

The crunching noises are typically due to a binding upper strut mount. Reach over the top of the tire and loosely wrap your fingertips over one of the coils on the spring, then have a helper slowly turn the steering wheel back and forth. The strut and spring should rotate with the tire smoothly. If the upper mount is binding you'll feel the spring wind up, then pop free and turn once the tension gets high enough.

That alone doesn't require replacement of the strut or spring but there are other things to consider that we don't know about. Your mechanic could have seen the protective paint has flaked off the spring which will allow them to rust and break. Ford has way more trouble with separating steering and suspension parts that lead to loss of control and crashes than all other manufactures put together. If your mechanic sees any hint of a future problem and he has your best interest at heart, he is going to recommend the appropriate service. In this case, when a rusty spring breaks it is pretty common for one of the sharp ends to tear the sidewall of the tire and destroy it. Replacing the springs is much less expensive, (and can be considered normal maintenance), than having to buy springs AND tires later.

Springs also sag with age and let the car sit too low. Every alignment mechanic has a small book that lists every car model, where to take the measurements, and what they must be. Ford is also famous for neglecting to design in the normal alignment adjustments on their front-wheel-drive cars. You will get accelerated tire wear but with no adjustments provided, the only thing the mechanic can do for you to somewhat reduce that wear is to keep the suspension system at the correct ride height, and that means replacing the springs when necessary.

Struts are also a commonly-replaced item. That is when you will often be told, (after they've given you a written repair estimate), that additional parts are needed. For example, the upper strut mounts can be rusted apart inside or falling apart and there's no way to know until they are disassembled to replace the struts. That can be frustrating for owners and mechanics. A lot of mechanics just include those extra possibilities in their estimates, then surprise you with a bill lower than the estimate if those parts weren't needed. They run the risk though of losing the job because a competitor down the street didn't plan for those surprises and gave you a lower estimate.

Since struts are a normal maintenance item that you can expect to have to replace, and the upper mounts often develop problems, most of which can't be identified until after they're disassembled, and since all springs do sag, many aftermarket suppliers offer complete new assemblies. That addresses all the potential concerns. No dangerous spring compressors are needed, diagnostic and inspection time is greatly reduced, and labor time is so much less that the savings more than covers the cost of the parts.

There's too many variables to know why your mechanic made the recommendations he did. If an upper strut mount is needed, that should be all that is replaced. If a spring is needed, I'd like to know why, then they are always replaced in matched pairs. Once he's in that far, it is silly to not install new struts. That's like going through all the work of taking a shower, then putting on old socks! The exception would be if he knows the struts aren't very old.