you don't simulate HRTF and a room with a simple slope starting at a more or less arbitrary point, a delay picked by somebody else, and no reverb. fairly often the center voice takes a hit with default crossfeed and it can end up being just as annoying as the "double mono" effect from usual headphone use. I personally use some sort of crossfeed on everything headphone or IEM related(ok not on podcasts), so I don't need convincing about how I crave for anything taking me away from default headphone stereo and most albums. but if I had to pick a side in that long ping pong game between you and pinnahertz, I would more often take his side. because while crossfeed is at least to me a step in the right direction and much better than nothing, it's an incomplete approach. customization from measurements at the ear is the right approach. if speaker sound is what we desire, then room simulation is the right approach. and in front of it, crossfeed is more like a flawed toy.
crossfeed is amazing because of how cheap and readily available it is compared to better stuff. but it's not the answer, it's a lousy band aid until the industry admits that customized solutions are the only path toward actual headphone hifi.