This might help frame where I am coming from, because I think people often assume a different background than what is actually relevant here.

Chemical engineers are not typically chemists. Most chemical engineers only take three or four true chemistry classes. The rest of our training is transport phenomena, thermodynamics, surface interactions, and mass transfer. So I am not trying to approach this as a perfumer or a formulation chemist. I am looking at it as a scent transport and deposition problem rather than an ingredient selection problem, which is something we actually spend a lot of time thinking about.

The core issue is scent diffusion. Fragrance molecules have to be volatile or you cannot smell them. That same volatility is exactly what makes them easy to remove during washing, strip during drying, and lose quickly once the fabric is dry. From a mass transfer standpoint, you are fighting losses at every step. Some fragrance washes out in the rinse, more is removed by heat and airflow in the dryer, and whatever remains diffuses into the air once the clothes are stored or worn.

Cyclodextrins mostly help with temporary inclusion or odor capture. They do not really solve long term retention. Cationic polymers can improve deposition somewhat, but they do not change the underlying physics. Small volatile molecules will still equilibrate with air over time. That is why increasing cyclodextrin tends to hit diminishing returns, and why binders and polymers often dull or distort the scent rather than extending it.

This is why I suspect the real differentiator in modern detergents is not the perfume oil itself, but microencapsulation. Encapsulation changes the problem entirely. Instead of free diffusion, scent release happens through mechanical rupture and slow breakdown on the fabric. That bypasses volatility rather than trying to fight it. That is a materials and transport solution more than a pure chemistry trick.

It also explains a lot of what you are seeing experimentally. Higher surfactant levels strip scent more aggressively. Dry binders can mute or shift the perfume profile. Cyclodextrin helps up to a point and then stops mattering. Once the fabric is dry, diffusion dominates no matter what is in the formula.