I find it a bit odd that people do so much service. Is there something about modern chain oil that makes it less effective than in the 80s? I'm pretty sure I forgot the chain most years, though whatever bike I had was always an example of survivor bias.
Modern derailleur systems use very narrow chains that won't tolerate being dirty. A hub gear setup with a 1/8" chain (or an old 5-speed derailleur setup) will tolerate much more abuse. A traditional roadster bike (stadsfiets) with full-length mudguards and an enclosed chaincase throws much less dirt into the drivetrain than a sporting bicycle with neither.
It all depends on how many watts you want to lose to chain friction and how quickly you want to wear other components out with the sandy oil slurry on your chain. If the answers are "I can tolerate tons of lost watts because it's an ebike" and "the components are cheap, who cares" then maybe running a dirty chain for ages is acceptable.
I don't know if it's actually necessary, but it's the upper end of the recommendations I've seen/heard, and I noticed a surprising improvement in performance after I cleaned/lubed it.
I assume it's also more important on e-bikes (and especially cargo e-bikes) since the chain sees higher forces over longer periods of time.
Maybe more important, however in my experience these things are neglected more often with ebikes than traditonal bikes, because the motor compensates the dirty chain or if the tyres could use some air... ;-)
