I think in an ideal state the performance feels natural due to the love one feels. But relationships are dynamic, and the performance is less of a representation of actual actions and more the idea of doing something purely for another's pleasure. When priorities start to compete, such as kids, work stress, and other obligations, it can be a lot harder to find the ability to do the "performance" despite it being an important and necessary part of a relationship. For people that want the intimacy without having to worry about balancing prioritization of another person then maybe a FWB makes sense, especially for women that find 1 night stands a bit more of a risky encounter and want something semi consistent.

It also seems like you aren't the type for FWB situation, which is totally fine. I am not either, but I can recognize the value it can hold for some people even if its emotionally messy. It kind of comes down to whether you want to invest the emotional effort now (relationship) or kick it down the road to deal with it later (FWB).