I wouldn't say it's addicticve for the engine, as it is used to suppliment a fueling or ignition problem that is already present. Where nobody has fixed - therefore gets worse, and so you need to use the EZ start more often...but I do find the smell rather intoxicating
We just traded in our old AWD 7,5tonner (basically an old Bedford TF with a 6.0l turbo Perkins
). And that had a cold start primer which would spray into the intake - wasn't easy start though, just alochol (I think). Never ever needed to use - would always start on the button come rain snow or shine - no glow plugs either.
I used to fire my Landy up on it as the (mechanical) fuel pump kept drining back after it had been left standing, was a case of get a mate to hold the starter, as I sprayed and stood well back (it liked to spit flames
)