If you lose your Warrior
Maybe you should have gotten more than one...
There's an odd number of Warriors, so somebody always gets an inherent (dis)advantage (except in 5er).
The Page line has had two key major shuffle moments whenever I've played it (and yes a couple of times I've bought nothing but Pages to start, draw a bit later): Warrior killing Warrior and Warrior flipping Champion(Hero)/Champion(Hero) being bottom decked.
Sometimes Champion doesn't matter at all, you can easily cycle your deck ... but those also seem to be the boards where Champion isn't worth the bother so much. When Champion is most worth getting it seems to be for stuff like taking a slow BM-esque board and warping it into a light speed super engine board. Flipping a Champion/Hero can be the functional equivalent of gaining 2 or 3 turns on your opponent. Worse, it can easily stack up where Champion/Warrior/Page can kill off a lot of cards really quickly. Worst case is something like pre-Champion you play maybe 7 cards. Post-Champion you snap up a few Smithies and play a not-fully-trashed deck every turn. Flipping Champion can easily mean that the unlucky guy has to wade through 4 turns before they can draw deck and by then the deck drawer can do A LOT of damage (or buy out many points)
Even when Warrior killing Warrior is completely averted (say you can easily manage to always have Lighthouse out), you still get some really swingy results based on when Champion gets played.
So yeah, the Dominion cards I most dislike are the ones that have very high variance, don't allow for a lot of tactical adaptation, and have very unique effects that make games very annoying when the game can come down to single shuffles.
Again, none of this is to say that the Page line are bad or anything. I, and the people I tend to play with IRL, don't like Possession, Swindler, or Rebuild in large part because one shuffle is so important. That's life. The fact that we have that luxury is just because Dominion is so well done that it tends to be the exception and not the rule.