PET bottle recycling is the only part of plastics recycling that actually works. Making sure the bottle caps are also correctly returned to recycling plants is a good goal. Also it makes picking up litter a little easier, because now you only need to pick up one thing instead of two.

Btw, this is why clothing/bags/… made out of recycled plastic bottles is actually a terrible idea, because once the PET is out of the bottle recycling stream it is permanently removed from this recycling loop and new PET needs to be produced to compensate.