How can both of your points be true? If the owners are the problem then you can't really evaluate the actions of those under them. In the same way, we can't blame players if a manager is shit, we can't blame a manager if his manager is also shit. The thing is Rangnick called out the structures above and playing personnel below. Whether or not you agree that that was the right thing to do as a manager, you can't deny the facts about what he said. Everything he said was evident, Even the suggestion of the razing of multi-million assets we've gone and done anyway so he wasn't wrong there either.
Of course, any dimwit can see what's going on wrong with our club, but only a few people have the qualifications to fix it. The options the club had then were a) Stick with Rangnick, who was undoubtedly qualified for the role, b) hire a qualified DoF with similar or better experience than Rangnick, or c) keep the status quo. We chose to go with C. A bigger grift in my opinion.
Sure, Rangnick may have gone on to sign flops as well, but I believe signing player X under the reformed structures of the club, which he would have been involved in shaping, would have given the player a better chance to succeed than signing the same player X into our past and current structures. We have that many flops because we don't have the required platform for signings to succeed.
This is not even a Rangnick issue. Every single manager has complained about the club's way of doing things after they had left. He was the first person working within the club to call out the club's structures and players. Crucially, he also had the experience of fixing the damn thing he was complaining about. This isn't the same as a regular fan pointing out these same obvious issues. This is what irks me most when people argue that anyone could see what he saw, anyone could recommend players, etc. Unless this "anyone" excludes the current people in charge of running the club because seems they are the only ones not seeing it.