I fail to see how anything in this safety notice, apart from the battery part, is news.
The battery part also can only be called "relatively" new.
In my 20 years as CC this problem has always been present, as it will be until time's end.
All you can hope for is a company that actually backs CC and FC when offloading, asking for PAX to stick to published limits is obviously not realistic.
Mind you, there are of course many Passengers who DO come abord with baggage within limits. Still, there are enough who don't.