There's lots of pushback against training wheels in the enthusiast community. I've drunk some of that Kool-Aid myself, but now I'm not so sure that there isn't a place for these devices after all.
Tuesday I was in Millennium Park in Chicago whiling away a few minutes prior to a meeting. Saw a mother strolling the paths with her young daughter who was pedaling along on a training-wheel bike. Daughter was maybe four. (Just a guess). Mother walking. Daughter Pedaling. Both enjoying the day. It is difficult for me to imagine that scenario playing out with a balance bike. What kid is going to want to kick the bike along with her feet for that sort of distance?
Then there is my neighbor's experience. He bought a balance-bike last year for his son, and his son would not, and still won't, touch the thing. Zero interest. Nada. The kid is not dumb, and sees that everyone else has pedals. This year the kid has a pedal bike with training wheels. He'll ride that one, but never the balance bike. (He rides a kick-scooter however, and surely is learning some balance from that).
Two years ago I'd have said reflexively to avoid training wheels. These days I'm not so sure.