I'm not an expert but I think it is important to learn a RPB flat counter drive. That is not a super useful stroke in matches but it will help you to learn passive and active blocking with RPB.
Dang qiu does that very well, he can switch between rpb block, rpb active block and topspin on the BH so he is not easy to beat there.
Just saw the Chinese penholder (ranked like 500) destroy korean top50 player an jaehyun
Not sure if that guy has the potential to be a top guy, probably not especially since he plays forehand pips apparently but he has a very strong RPB passive game. Good rpb blocks and also RPB punches and "active blocks" where he kinda does like a mini topspin with the wrist.
I think that is an important skill for RPB players, dang qiu improved that quite a bit too. RPB is good to open up and flip over table but many seem to struggle with passive game when BH is attacked.
I think if you have a good RPB passive game that makes it harder to attack you as a penholder so you can kinda wait for a chance to attack with FH without getting too weak.
I'm not an expert of course but to me that looks like an important feature for modern penholders.