Not sure why Rieder is exempt from this. The dude hasn't scored a goal this year. He is a complete non-factor, actually quite detrimental to the success of this team. He, Spooner, Lucic, and a few other forwards are horrifically bad.
For me it's because:
1. He's only on a 1 year contract, we can easily cut him loose if he continues to suck.
2. We acquired him for free, without losing any valuable assets.
3. He played well before the injury, coming back to a new coach + system is difficult.
Those reasons put him lower on the ladder when I try to identify what the biggest problems with this team is. All of my usual targets of criticism are those who we're stuck with. Lucic, Spooner, Kassian, etc. The end goal of this team is to build a cup contender around McDavid and Draisaitl. Rieder failing here would just be a small blip, negligible in terms of any long term effect.
Also I should add, those are pretty much the same reasons I didn't really like to shit on guys like Khaira earlier this year.