You can still cause significant lag using relays, and someone with a bad connection may crash.
It's called trusting the people on your server not to do it. I know you can't trust everyone, but you learn that through experience, not through some bullstuff-proof add-on.
Save often and be a Watchful Admin. Do add-ons have to do everything for you?
Also, the maximum relay speed cannot exceed 30 seconds unless otherwise counted by variables. Its never been able to, to my knowledge. It's the minimum relay speed you should be worried about
No you can't cause significant lag with relays, you're overestimating how much time it takes to process them.
There are bad people in blockland, not a valid comparison.
What on earth do you mean "Do add-ons have to do everything for you?" ??? They're CAUSING the problems!
By maximum relay speed I mean how fast you can fire relays, which is somewhere between 33-66ms, enough time to process over 1 thousand relays, so again, relays are nothing to worry about.