It is not the prior lore, it is the new lore they published in the UA.
In the UA they said the "PDKs are paragons of valor ... rally to the causes of justice and freedom .... protect the innocent ... enlisted from any realms where chivalry is in abundance ..."
I think what Banana is saying is those traits do not go with Amethyst Dragons. It fits Gold Dragons and Silver Dragons, but Amethyst Dragons are aloof and detached and are NOT these things.
Unless they are going to wholesale change the lore on Amethyst Dragons as well.
Somewhat, yeah. The noble and valorous order of leaders and knight allying with these aloof dragons who learn about planar balance is not an
obvious pairing, and the UA didn't offer any reason for it, which leads to wild mass guessing like "lol, they just shoehorned the game's purple dragons into the Purple Dragon Knights," which, without other evidence as to why they're smashing these two things together, certainly isn't out of the realm of possibility.
A Gold or Silver or Bronze dragon would've made more intuitive sense. In that case, my critique would've definitely been more in line with "this is just a bad subclass design."
PDK riding purple dragons dont even make sense with current lore models.
That doesn't mean the story of allying with amethyst dragons
can't fit, of course. A subplot about the Far Realm or Mind Flayers or something could tie the two quite comfortably together. And, I'm fond of the tension that could exist between the noble intent and reputation of these valorous knights and the significantly less altruistic or honor-bound dragons that they've allied with. That kind of conflict - allies who want very different things - is a rich vein for storytelling, and it could be a very mature kind of plotline where stated and closely-held ideals chafe up against practical considerations, the responsible use of power, and maybe even an effective defense of the world. If WotC leans into the tension and allows Cormyr to become a little more complex, that story could certainly go interesting places.
Of course, they could just go "Now the Purple Dwagon Knights have purple dwagon fwiends because the dwagons are cool and are good to their fwiends wheeeee!
airplane noises" and not explore any of this, and that would be dumb. And they could just leave it completely unexplained like they did in the UA, and that could arguably be even dumber.
And because this is the first significant supplement of a new "edition" and a new leadership team, the scrutiny is extremely high, since this could signify what the next 5 or so years of the game are like. Are we going to try and respect the lore? Advance stories in interesting and story-rich directions? Deal with kind of grown-up topics like the fragility of alliances and how power groups can use each other and if it's possible to maintain your ideals when you ally with people who don't share them? Or are we going to be dealing with a leadership team who thinks things like "Purple Dragon Knights should be friends with purple dragons!" is a good basis for design and storytelling, so good, in fact, that they're ignoring or being deaf to a fandom that is telling them that it is not, in fact, good? Is this going to be a fun run of the edition cycle that adds and expands and develops things, or one that is going to involve tolerating the team's pet ideas of what is good for the game regardless of if they're good or not?
Either way, though, the UA subclass was definitely Not It.