Mad props to the props
There's an attractive simplicity in needing nothing but a mat to practice yoga. But as soon as you start bringing in bolsters, blocks and belts to the mat, it can feel like a lot of unnecessary gear getting all up in your business. Everyone experiences the urge of wanting to get to a point where you don't need any of these props in your practice, kind of like a kid wanting to get rid of the stabilisers on a bike – but it's the wrong way to look at yoga props.
For anyone focussed on alignment, they're essential to any and all body types. Without a folded blanket for instance, there's an argument to say you'll never get into a shoulder stand correctly or safely – our bodies just aren't designed that way. In Iyengar particularly, your teacher will have you strapping limbs in place with a belt to help you with engagement or opening, and generally expose that you can't do the yoga poses anywhere near as well as you initially thought.
Beyond alignment though, props also help you relieve pressure from areas of your body (like the lower back) and set you on a faster trajectory towards any 'end game' of poses you're working on. They're often actually the short-cut to getting the full posture. Helping you figure out and switch on the right muscles, while simultaneously relaxing others so that you can learn to go a little deeper, find a bit more space in your body. And that's pretty much why we're here – to create space. And space equals comfort.