I understand what you are hearing. Absolutely, without DSP the discreet channel will be clearer. However, these discreet channels are meant to be heard with a bit of natural reverb, with room reflections that will naturally soften the sound. The audio engineer accounts for this, and the mix, positioning of instruments are created with this in mind.

A trick with any type of listening is that your brain acclimating to the sound. After listening to spatial DSP for a while it beings to sound more natural, and then switching back to regular stereo will sound incorrect.(hard-panned, no center channel, less depth, etc).

Furthermore, with multi-channel sources, if you are listening without DSP, there can be issues with the mix-down. In some cases the center channel isn't blended with the right volume etc.

I've tested Dolby Atmos for Headphones quite a bit using Focal Utopia for reference. The only thing that beat Dolby was Waves Abbey Road Studio. But this is a pro studio plugin and tricky to setup. It had very little artifact in its sound. That said, I'd put Dolby Atmos for Headphones up there. If you do try it again, check the settings. I believe the Gaming mode is actually clearer than the cinema settings with less overall reverb. it gives you a tighter spatial soundstage, with less spectral delay. It is more akin to listening to studio monitors.