I only think there's one rider who you'd mistakenly think had won a WC title in MTB, cause why wouldn't she have? Much like how it for many years just seemed natural that Leonardo DiCaprio was an Oscar winner, despite it not being the case until he won for The Revenant in 2016. However this rider's MTB career was actually quite short-lived and not that impressive, and it ended a long time before 2024.
We're dealing with the most succesful female rider in history, and although she has a lot of non-road accomplishments as well, she'd still be the GOAT if you took away all of them, and therefore it just sounds wrong to claim she isn't mainly known for her road results. Riders like Pauline Ferrand-Prevot, Lucinda Brand, Fem van Empel and Puck Pieterse at this point in time are more famous for their feats off-road, but that just isn't the case for someone who's won over 250 victories on the road.