Is there any harm in modelling Likert scale data using an lmer() model? I have 140 participants, each making 70 ratings. The DV is a seven-item Likert scale.
I've read conflicting things about modeling this sort of data with a plain lmer() model.
I'm curious what the current consensus is?

Since your goal with the model is prediction and not inference, I don't think there is any harm in modelling a 7-point Likert scale outcome as continuous with lmer. I would, however suggest comparing it with other approaches such as cumulative link mixed model.
