Can you define what ‘early challenging content’ means to you ? I mean it in a concrete, factual way. (and I hope it’s not perceived as condescending)
Since you can go as fast as you want and choose your fights (what POE2 absolutely hates and refuse you to do with the movement speed debate right now elsewhere), you can easily just rush some campaign zones, gets fewer but more challenging encounters and get rewarded for it (by just… not wasting time).
I had the same stance as you, but i’ve changed my approach* after starting ‘speedrunning’ (with amateurish attempts).
Now, my encounters are spicy, I do campaign (the 15/8 in SCF) under 4 hours (and I think I can get under 3h30 with some masteries), and I don’t feel the slog anymore. I feel like I was wrong asking for a more challenging campaign : I was just slow and sticking too much to zones. Now I skip some zones and I feel way more engaged with what I do AND I get to a proper build so much faster.
I think I kinda need to apologize for posts where I was asking for harder content early game. I was just staying in zones too much. Plus, EHG finally seems willing to gives players tools to skip some content and gives them agency to what/how they progress with the new dungeon passives/idols rewards. I can’t wait to find ways to be better and faster.
So, I genuinely ask you : is it possible that you don’t engage the game in the best way it could be for you ? It is presumptuous but sometimes, the game wants to meet you ‘halfway there’, you know.
But also, maybe the game is not for you and that’s absolutely okay. Take care!
*Okay, language question. In french we say “Changer son fusil d’épaule”, which translate to ‘Switch my rifle … from one shoulder to the other one’ ? Google says that the translation is “change one’s approach”… it gets the meaning but the image is so far off, I’m wondering if there is an equivalent expression in english ? Sorry that’s random and irrelevant but I’m curious 
Edit : I still think that the masochist boots were an arrogant and lazy insult to players that were asking for challenge. Like “Oh, you’re so cute, you want a challenge. Here! Suffer for no reason, you dumby-dumb-dumb”. Still hate it the way it was conveyed and offered.