imagine if they tried to respend right at that 6th block. the next maturity is 2 hours..
where as everyone else that only spends once or twice a day, or week or month never gets maturity locked out, because it matures before they need to respend. but know they can respend because the waiting time is AFTER confirm.. thus they know they have been paid. instead of the current setup that delays due to spam leave them waiting before confirm and unsure if they will be even paid..
thus ethical people can spend when they want and malicious people are ending up having to wait.. and its all done by code rules.. not 'fees'
the problem is that they are not using "100" not even "1000" addresses. it goes so much deeper than that.
here is the last time this happened:
https://bitcointalksearch.org/user/coinwalleteu-553487
this is the tip of the iceberg and there are about 820 keys there used in the spam attack, each address containing lots of transactions (about 10K to 40K outputs) to spend.
and this is only the private keys they released to fool others into making transactions with the inputs and join in the attack. they also had other addresses which were sending out transactions on a massive scale.
thats where
one guy makes a single TX of say $1 to send to 1000 addresses of $0.001 .. and thats it. game over.
but other spam attacks that cause more hassle long term is where
one guy makes a TX of say $1001 to send to 1000 addresses of $1
then 10 minutes later sends all them $1 transactions to another address combining the funds
then 10 minutes later splitting the funds back to $1..
then 10 minutes later sends all them $1 transactions to another address combining the funds
then 10 minutes later splitting the funds back to $1..
then 10 minutes later sends all them $1 transactions to another address combining the funds
endlessly.
this is when devs think they can mitigate this type of spam attack by raising the fee to make the guy lose alot of his $1000 investment each time he respends.. but the reality is that it just prices ethical/moral people out of using bitcoin less often.
however a maturity lock stops this endless spam without the 'penalty' hurting innocent people