I would argue yes, at least for Plato in particular, the commentaries take their time to discuss the topics in the so-called "Socratic" style, and its easy to e

I would argue yes, at least for Plato in particular, the commentaries take their time to discuss the topics in the so-called "Socratic" style, and its easy to engage with the arguments and counter-arguments directly. I think with a commentary you risk reading someone else's opinion, without challenging yourself to form your own. It's more-or-less equivalent to doing the exercises in a math text rather than just reading the chapters and letting the author convince you that you understand. Obviously the ideal is the read the source material and then read commentaries after once you've had a chance to reflect on it for yourself. Of course for me, I have only ever managed to read Plato and Karl Popper. Other "Classics" like Hume or Kant I can't make heads of tails of the source material without some guidance. I haven't even tried the most notoriously dense authors like Nietsche or Hegel.