I find pull downs beneficial (at least they feel good and make my shoulders feel better) but I think it depends on how you do them.
I find it important to use low enough weight so that the lower and mid traps are working and not being overpowered by other stronger muscles.
Also I use slow and steady speed so that I can not cheat parts of the lift using momentum.
Also I start with shoulder blades up and the first phase of each pull is just pulling the shoulder blades down. In other words I try to bring my arms down as far as possible without bending them. From here on I keep them locked down.
Moving the shoulder blades up and down instead of keeping them down put less emphasis on the lats (1) which is a good thing since the lats are internal shoulder rotators.
Also I pull towards my chest while I bend/arch backward and press shoulder blades together. At this stage the pull down almost turns into a horizontal pull (inverted row). I notice that some (2) discourages this. Instead they say that you should stay as vertical as possible to maximixe lat engagement.
But this is exactly what we want to avoid.
I guess if lat involvement really is a problem you may be better of only doing the initial pulling shoulder blades part down of the pull down.
I think it is wise to alternate between vertical and horizontal pulling.
(1) Muscle and Motion: Lat Pulldown
(2) Lat Pulldown Master Class