And Paarthurnax Apologists are assuming that the Dragon that says "don't trust Dragons" is to be trusted.
Well, if dragons aren't to be trusted, and the dragon tells us not to trust dragons, doesn't that mean we should trust dragons?
I don't believe Paarthurnax deserves to die for atrocities I don't even really know the details of. As stated above, the people who want him dead want him dead because he killed people trying to kill him. That sounds like self-defense to me.
If Paarthurnax does try to replace Alduin (which seems highly unlikely to me), I'll deal with him then, but I won't execute someone because he might do something bad down the road.
Well if you go with the Greybeards, your dead. So nice knowing ya.
As far as the Blades, again if I were them I would do the same thing. They think it's all over and low and behold here come dragons and ... a Dragonborn. They know historically they helped the Dragonborn. Of course they want to use the Dragonborn to restore their order. I'd do the same thing. Of course slaying all the dragons is a great way to get recognition. I'd do that too. Wanting P dead is their only fault and I can forgive them that also based on the history they are using to come to that decision.
Don't get me wrong I like P and all my Nords that did the MQ let him live. The Imperial and Orc I played that did the MQ however rather the Blades were restored.
Like I said, the Greybeards don't try and restrict me, so I'm free to do what I want. I'll save the world without them, and they can continue meditating and trying to achieve enlightenment. We both win.
The huge difference between what the Blades used to be and what they are now is clearly defined in your post. "...they helped the Dragonborn," vs "...they want to use the Dragonborn..."
Those are two very different verbs. If they genuinely wanted to help me, they wouldn't offer me that "You're either with us or against us" ultimatum later in the main quest. But the fact of the matter is they are only trying to use me. They are completely dependent on me, and aside from a bit of useful data here and there (which they only give up when it suits their own purposes), they offer me very little.