Not totally true. My Thai son, his Thai wife and his 4 kids love it. Years ago my Thai son gave his Thai mother in a piece of toast with Vegemite, now she asks or it along with the fresh hilltribe coffee we make for her (she previously always drank 3 in 1).
We bought her a jar of Vegemite to take home to Tak.
She's the village chief, she buys local bread, slices it, toasts it and adds Vegemite, the kids in the village love it / ask for it.
Sure it's not for everybody.