When blocks are full, anyone will be able to shut it down for an hour for $100,000. It will be slow for many hours after that. That's your idea of security?
What's 100 grand to stop a six billion dollar network? You just gave the banksters a kill switch.
What's 100 grand to stop a six billion dollar network? You just gave the banksters a kill switch.
Please show us where, among the numerous previous periods of full blocks, the network was 'stopped'.
It never happened. End of story.
Edit: Also, what does 'shut it down for half an hour' have to do with 'security'? When, during this fabricated scenario of yours, did people's coins get stolen from their wallets, or people magically have funds appear in their accounts?
If fees are running 5 BTC/block, you could pay let's say 10 BTC/ block and almost completely fill it up with transactions sending money to yourself. Greedy miners could do this every time the fees got too low and keep the fees at whatever nash equilibrium level they want.
The fee market is just as subject to manipulation as any other market. Sure, some transaction will just stop being made as no longer cost effective, but some will have to be made no matter what fees are attached. These transactors will continue to try and out bid each other for block space even after the spam attack is over.
So if someone perhaps wants to roll out Bankstercoin, they could dramatically slow down bitcoin for a few hours or days to snag some market share. Or traders could make a big leveraged short along with a spam attack and force a long squeeze. All it takes is filling up 144 blocks to put the whole network a day behind.
Governments and central banks could kill Bitcoin for weeks with pocket change, just to ensure it never provides a better value than SWIFT, ACH, Western Union or whatever. A tiny fraction of the War on Drugs Budget and the War on Terroism budget could make Bitcoin as unreliable as a third world power grid.
Previous periods of full blocks didn't have as many people who NEEDED not just wanted the network to work. The more people who NEED it to work, the more vulnerable it is to a spam attack. The blocksize limit is an effective way to not just keep bitcoin small, but to keep it unimportant.