"just a reminder that the Monero blockchain is going to be linearly larger than Bitcoin's when it reaches the same amount of use!"
Incorrect on 'linearly'. Bitcoin can theoretically be pruned. Monero can't theoretically be (prove me wrong).
most certainly not in some half-baked way that has potentially far-reaching and devastating consequences.
And I agree that BoolBerry's pruning probably has a flaw that inevitably leads (or is vulnerable) to some divergent scenario such as gridlock or simply isn't what is claimed. I would need to look closer to be sure, and I don't have time. But I remember thinking about the possibilities in some detail months ago when I learned of Cryptonote and I always thought of divergent scenarios to every pruning strategy.
As I said upthread, any user you mix with can stop pruning for everyone else in the mix by not spending his coin, thus there are not enough spends on the ring to prune it. And rings can overlap each other thus the number of independent variables in the pruning equation can explode.
Even if force everyone to spend their coins periodically, that just shifts the problem forward in the blockchain and doesn't solve it.