You'd be wrong. There are many features in HDMI that have no equivalent in DP which are virtually essential in the modern AV setup, things like eARC or CDC passthrough.
DP is by far superior on an electrical signalling perspective. But the best tech means nothing if you're unable to use it effectively. At the end of the day, features win out and consumers won't be interested in replacing a couple of HDMI cables for a shitton of separate AV cables.
Actually I don't think there's actually a way to properly implement some modern AV features without HDMI, as some of the modern audio codecs require more bandwidth than what traditional audio links (not the ones bundled with video) are capable of, and the lack of two way audio features in dp open you up to a shitton of messy cabling and switching TV and AV receivers independently like we did in the late 90s Dolby Pro-Logic II days.