If it's not D&D in the strictest sense, then it's not 5e in the strictest sense since 5e is an edition of D&D. Further, sharing a lot of DNA with something doesn't mean much. Humans share roughly 98% of our DNA with chimps.
At what point does it not become D&D if it simply shares a lot with WOTC's (or TSR's since it's general means it's not 5E specific) D&D? Does Daggerheart qualify? PF 2? I don't have an issue with bringing in supplements or other games. Just be clear about it.