@adamstgbit The orphan risk analysis still applies. Why risk a significant chance of losing $100,000+ in an attempt to gain $500?
But if that's not convincing, I thought of a new angle on all this.
To echo
@awemany's old observation, somehow putting software between a bunch of humans making decisions fools us into thinking it isn't just a bunch of humans making decisions.
And how do humans make decisions on things like what blocks they will mine and mine atop? They communicate to get a feel for more detailed guidelines than just those for the
size of blocks. Most miners may have a "reality check" hard limit of 1GB (for now) hardcoded into their software, but through normal communication via miner consortiums and standards committees, a miner can be quite confident of the conditions that will allow their block to be accepted. Miners should be running stress tests with each other constantly to determine what parameters are definitely safe and when, below any hardcoded limits.
It could be something like a consortium of 80% of the hashpower agrees to orphan any blocks that are very large compared to their fee total, or the average size / fee total recently. Miners not deterred by "hard" network orphan risk have to contend with this additional soft orphan risk. They also might be excommunicated. They also might be concerned with price drops due to people being up in arms (rightly or wrongly) about their "full node" being bumped off.
There are a lot of factors, and as I've said before it works like a Keynesian beauty contest, where the ladies are blocks: you've got to choose the block you think the majority is most likely to accept. This folds back in on itself with the result that miners are rather conservative
even within the softer guidelines and won't do things like try to screw over poorly connected miners (what pool is so tiny as to not be able to afford fast connectivity anyway?).
The same applies to removing the cap completely. Again it's not like devs set policy; miners do. BU makes the point clearest, as usual, because it lets any miner remove any "reality checks" if they choose to. Bitcoin survives by mining incentives, so no need to babysit them anyway.
What some picture when they think of having no hardcoded blocksize cap is something like, "This software will *force* you to accept a block no matter what the size." No software can ultimately force you to do anything, but BU (and ABC) doesn't even try to do that. It lets the user decide, because it doesn't bake in a "devs are part of the governance structure" philosophy into its code, unlike Core.